diff --git a/tests/legacy-cli/e2e/tests/basic/rebuild.ts b/tests/legacy-cli/e2e/tests/basic/rebuild.ts
index 486e6d3fb2c1..a1af3e836328 100644
--- a/tests/legacy-cli/e2e/tests/basic/rebuild.ts
+++ b/tests/legacy-cli/e2e/tests/basic/rebuild.ts
@@ -7,12 +7,15 @@ import {
 import { writeFile, writeMultipleFiles } from '../../utils/fs';
 import { wait } from '../../utils/utils';
 import fetch from 'node-fetch';
+import { findFreePort } from '../../utils/network';
 
 const validBundleRegEx = / Compiled successfully./;
 
-export default function () {
+export default async function () {
+  const port = await findFreePort();
+
   return (
-    execAndWaitForOutputToMatch('ng', ['serve'], validBundleRegEx)
+    execAndWaitForOutputToMatch('ng', ['serve', '--port', String(port)], validBundleRegEx)
       // Add a lazy module.
       .then(() => ng('generate', 'module', 'lazy', '--routing'))
       // Should trigger a rebuild with a new bundle.
@@ -136,7 +139,7 @@ export default function () {
         ]),
       )
       .then(() => wait(2000))
-      .then(() => fetch('http://localhost:4200/main.js'))
+      .then(() => fetch(`http://localhost:${port}/main.js`))
       .then((response) => response.text())
       .then((body) => {
         if (!body.match(/\$\$_E2E_GOLDEN_VALUE_1/)) {
@@ -158,7 +161,7 @@ export default function () {
         ]),
       )
       .then(() => wait(2000))
-      .then(() => fetch('http://localhost:4200/main.js'))
+      .then(() => fetch(`http://localhost:${port}/main.js`))
       .then((response) => response.text())
       .then((body) => {
         if (!body.match(/testingTESTING123/)) {
@@ -174,7 +177,7 @@ export default function () {
         ]),
       )
       .then(() => wait(2000))
-      .then(() => fetch('http://localhost:4200/main.js'))
+      .then(() => fetch(`http://localhost:${port}/main.js`))
       .then((response) => response.text())
       .then((body) => {
         if (!body.match(/color:\s?blue/)) {
diff --git a/tests/legacy-cli/e2e/tests/basic/serve.ts b/tests/legacy-cli/e2e/tests/basic/serve.ts
index 9078c4779fd0..f0e893f2c538 100644
--- a/tests/legacy-cli/e2e/tests/basic/serve.ts
+++ b/tests/legacy-cli/e2e/tests/basic/serve.ts
@@ -5,20 +5,20 @@ import { ngServe } from '../../utils/project';
 export default async function () {
   try {
     // Serve works without HMR
-    await ngServe('--no-hmr');
-    await verifyResponse();
+    const noHmrPort = await ngServe('--no-hmr');
+    await verifyResponse(noHmrPort);
     await killAllProcesses();
 
     // Serve works with HMR
-    await ngServe('--hmr');
-    await verifyResponse();
+    const hmrPort = await ngServe('--hmr');
+    await verifyResponse(hmrPort);
   } finally {
     await killAllProcesses();
   }
 }
 
-async function verifyResponse(): Promise<void> {
-  const response = await fetch('http://localhost:4200/');
+async function verifyResponse(port: number): Promise<void> {
+  const response = await fetch(`http://localhost:${port}/`);
 
   if (!/<app-root><\/app-root>/.test(await response.text())) {
     throw new Error('Response does not match expected value.');
diff --git a/tests/legacy-cli/e2e/tests/commands/serve/serve-path.ts b/tests/legacy-cli/e2e/tests/commands/serve/serve-path.ts
index 6217656a2a85..d5783b788363 100644
--- a/tests/legacy-cli/e2e/tests/commands/serve/serve-path.ts
+++ b/tests/legacy-cli/e2e/tests/commands/serve/serve-path.ts
@@ -3,17 +3,18 @@ import fetch from 'node-fetch';
 import { killAllProcesses } from '../../../utils/process';
 import { ngServe } from '../../../utils/project';
 
-export default function () {
+export default async function () {
   // TODO(architect): Delete this test. It is now in devkit/build-angular.
 
+  const port = await ngServe('--serve-path', 'test/');
+
   return Promise.resolve()
-    .then(() => ngServe('--serve-path', 'test/'))
-    .then(() => fetch('http://localhost:4200/test', { headers: { 'Accept': 'text/html' } }))
+    .then(() => fetch(`http://localhost:${port}/test`, { headers: { 'Accept': 'text/html' } }))
     .then(async (response) => {
       assert.strictEqual(response.status, 200);
       assert.match(await response.text(), /<app-root><\/app-root>/);
     })
-    .then(() => fetch('http://localhost:4200/test/abc', { headers: { 'Accept': 'text/html' } }))
+    .then(() => fetch(`http://localhost:${port}/test/abc`, { headers: { 'Accept': 'text/html' } }))
     .then(async (response) => {
       assert.strictEqual(response.status, 200);
       assert.match(await response.text(), /<app-root><\/app-root>/);
diff --git a/tests/legacy-cli/e2e/tests/i18n/ivy-localize-basehref.ts b/tests/legacy-cli/e2e/tests/i18n/ivy-localize-basehref.ts
index b55cffc22f8d..79854bfb193d 100644
--- a/tests/legacy-cli/e2e/tests/i18n/ivy-localize-basehref.ts
+++ b/tests/legacy-cli/e2e/tests/i18n/ivy-localize-basehref.ts
@@ -59,13 +59,17 @@ export default async function () {
     await ng('e2e', `--configuration=${lang}`, '--port=0');
 
     // Execute Application E2E tests for a production build without dev server
-    const server = externalServer(outputPath, (baseHrefs[lang] as string) || '/');
+    const { server, port, url } = await externalServer(
+      outputPath,
+      (baseHrefs[lang] as string) || '/',
+    );
     try {
       await ng(
         'e2e',
+        `--port=${port}`,
         `--configuration=${lang}`,
         '--dev-server-target=',
-        `--base-url=http://localhost:4200${baseHrefs[lang] || '/'}`,
+        `--base-url=${url}`,
       );
     } finally {
       server.close();
@@ -89,13 +93,17 @@ export default async function () {
     await ng('e2e', `--configuration=${lang}`, '--port=0');
 
     // Execute Application E2E tests for a production build without dev server
-    const server = externalServer(outputPath, '/test' + (baseHrefs[lang] || '/'));
+    const { server, port, url } = await externalServer(
+      outputPath,
+      '/test' + (baseHrefs[lang] || '/'),
+    );
     try {
       await ng(
         'e2e',
+        `--port=${port}`,
         `--configuration=${lang}`,
         '--dev-server-target=',
-        `--base-url=http://localhost:4200/test${baseHrefs[lang] || '/'}`,
+        `--base-url=${url}`,
       );
     } finally {
       server.close();
diff --git a/tests/legacy-cli/e2e/tests/i18n/ivy-localize-es2015.ts b/tests/legacy-cli/e2e/tests/i18n/ivy-localize-es2015.ts
index 70d49f5994cf..65fcfb0cbdbb 100644
--- a/tests/legacy-cli/e2e/tests/i18n/ivy-localize-es2015.ts
+++ b/tests/legacy-cli/e2e/tests/i18n/ivy-localize-es2015.ts
@@ -40,13 +40,14 @@ export default async function () {
     await ng('e2e', `--configuration=${lang}`, '--port=0');
 
     // Execute Application E2E tests for a production build without dev server
-    const server = externalServer(outputPath, `/${lang}/`);
+    const { server, port, url } = await externalServer(outputPath, `/${lang}/`);
     try {
       await ng(
         'e2e',
+        `--port=${port}`,
         `--configuration=${lang}`,
         '--dev-server-target=',
-        `--base-url=http://localhost:4200/${lang}/`,
+        `--base-url=${url}`,
       );
     } finally {
       server.close();
diff --git a/tests/legacy-cli/e2e/tests/i18n/ivy-localize-es5.ts b/tests/legacy-cli/e2e/tests/i18n/ivy-localize-es5.ts
index 8e996d396e85..5dbfbc402b7e 100644
--- a/tests/legacy-cli/e2e/tests/i18n/ivy-localize-es5.ts
+++ b/tests/legacy-cli/e2e/tests/i18n/ivy-localize-es5.ts
@@ -44,13 +44,14 @@ export default async function () {
     await ng('e2e', `--configuration=${lang}`, '--port=0');
 
     // Execute Application E2E tests for a production build without dev server
-    const server = externalServer(outputPath, `/${lang}/`);
+    const { server, port, url } = await externalServer(outputPath, `/${lang}/`);
     try {
       await ng(
         'e2e',
+        `--port=${port}`,
         `--configuration=${lang}`,
         '--dev-server-target=',
-        `--base-url=http://localhost:4200/${lang}/`,
+        `--base-url=${url}`,
       );
     } finally {
       server.close();
diff --git a/tests/legacy-cli/e2e/tests/i18n/ivy-localize-locale-data-augment.ts b/tests/legacy-cli/e2e/tests/i18n/ivy-localize-locale-data-augment.ts
index b1a9eaf307db..db45baf074b4 100644
--- a/tests/legacy-cli/e2e/tests/i18n/ivy-localize-locale-data-augment.ts
+++ b/tests/legacy-cli/e2e/tests/i18n/ivy-localize-locale-data-augment.ts
@@ -43,13 +43,14 @@ export default async function () {
     await ng('e2e', `--configuration=${lang}`, '--port=0');
 
     // Execute Application E2E tests for a production build without dev server
-    const server = externalServer(outputPath, `/${lang}/`);
+    const { server, port, url } = await externalServer(outputPath, `/${lang}/`);
     try {
       await ng(
         'e2e',
+        `--port=${port}`,
         `--configuration=${lang}`,
         '--dev-server-target=',
-        `--base-url=http://localhost:4200/${lang}/`,
+        `--base-url=${url}`,
       );
     } finally {
       server.close();
diff --git a/tests/legacy-cli/e2e/tests/i18n/ivy-localize-server.ts b/tests/legacy-cli/e2e/tests/i18n/ivy-localize-server.ts
index 82447344ad8e..91b598768302 100644
--- a/tests/legacy-cli/e2e/tests/i18n/ivy-localize-server.ts
+++ b/tests/legacy-cli/e2e/tests/i18n/ivy-localize-server.ts
@@ -2,6 +2,7 @@ import express from 'express';
 import { join } from 'path';
 import { getGlobalVariable } from '../../utils/env';
 import { appendToFile, expectFileToMatch, writeFile } from '../../utils/fs';
+import { findFreePort } from '../../utils/network';
 import { installWorkspacePackages } from '../../utils/packages';
 import { ng } from '../../utils/process';
 import { updateJsonFile } from '../../utils/project';
@@ -13,6 +14,7 @@ const snapshots = require('../../ng-snapshot/package.json');
 export default async function () {
   // TODO: Re-enable pending further Ivy/Universal/i18n work
   return;
+  const port = await findFreePort();
 
   // Setup i18n tests and config.
   await setupI18nConfig();
@@ -113,10 +115,10 @@ export default async function () {
     const { i18nApp } = (await import(serverBundle)) as {
       i18nApp(locale: string): express.Express;
     };
-    const server = i18nApp(lang).listen(4200, 'localhost');
+    const server = i18nApp(lang).listen(port, 'localhost');
     try {
       // Execute without a devserver.
-      await ng('e2e', `--configuration=${lang}`, '--dev-server-target=');
+      await ng('e2e', `--port=${port}`, `--configuration=${lang}`, '--dev-server-target=');
     } finally {
       server.close();
     }
diff --git a/tests/legacy-cli/e2e/tests/i18n/ivy-localize-serviceworker.ts b/tests/legacy-cli/e2e/tests/i18n/ivy-localize-serviceworker.ts
index 297e4225d179..c95fd000059c 100644
--- a/tests/legacy-cli/e2e/tests/i18n/ivy-localize-serviceworker.ts
+++ b/tests/legacy-cli/e2e/tests/i18n/ivy-localize-serviceworker.ts
@@ -8,11 +8,13 @@ import {
   replaceInFile,
   writeFile,
 } from '../../utils/fs';
+import { findFreePort } from '../../utils/network';
 import { installPackage } from '../../utils/packages';
 import { ng } from '../../utils/process';
 import { updateJsonFile } from '../../utils/project';
 import { expectToFail } from '../../utils/utils';
 import { readNgVersion } from '../../utils/version';
+import { externalServer } from './setup';
 
 export default async function () {
   // TEMP: disable pending i18n updates
@@ -154,9 +156,7 @@ export default async function () {
     await expectFileToExist(`${baseDir}/${lang}/ngsw.json`);
 
     // Ivy i18n doesn't yet work with `ng serve` so we must use a separate server.
-    const app = express();
-    app.use(express.static(resolve(baseDir, lang)));
-    const server = app.listen(4200, 'localhost');
+    const { server, port } = await externalServer(resolve(baseDir, lang));
     try {
       // Add E2E test for locale
       await writeFile(
@@ -180,7 +180,7 @@ export default async function () {
       );
 
       // Execute without a devserver.
-      await ng('e2e', '--dev-server-target=');
+      await ng('e2e', '--dev-server-target=', `--port=${port}`);
     } finally {
       server.close();
     }
diff --git a/tests/legacy-cli/e2e/tests/i18n/setup.ts b/tests/legacy-cli/e2e/tests/i18n/setup.ts
index d7954d6e5d59..816f3bd8f2ad 100644
--- a/tests/legacy-cli/e2e/tests/i18n/setup.ts
+++ b/tests/legacy-cli/e2e/tests/i18n/setup.ts
@@ -9,11 +9,13 @@ import {
   replaceInFile,
   writeFile,
 } from '../../utils/fs';
+import { findFreePort } from '../../utils/network';
 import { installPackage } from '../../utils/packages';
 import { ng } from '../../utils/process';
 import { updateJsonFile } from '../../utils/project';
-import { expectToFail } from '../../utils/utils';
 import { readNgVersion } from '../../utils/version';
+import { Server } from 'http';
+import { AddressInfo } from 'net';
 
 // Configurations for each locale.
 export const baseDir = 'dist/test-project';
@@ -67,13 +69,33 @@ export const langTranslations = [
 ];
 export const sourceLocale = langTranslations[0].lang;
 
-export const externalServer = (outputPath: string, baseUrl = '/') => {
+export interface ExternalServer {
+  readonly server: Server;
+  readonly port: number;
+  readonly url: string;
+}
+
+/**
+ * Create an `express` `http.Server` listening on a random port.
+ *
+ * Call .close() on the server return value to close the server.
+ */
+export async function externalServer(outputPath: string, baseUrl = '/'): Promise<ExternalServer> {
   const app = express();
   app.use(baseUrl, express.static(resolve(outputPath)));
 
-  // call .close() on the return value to close the server.
-  return app.listen(4200, 'localhost');
-};
+  return new Promise((resolve) => {
+    const server = app.listen(0, 'localhost', () => {
+      const { port } = server.address() as AddressInfo;
+
+      resolve({
+        server,
+        port,
+        url: `http://localhost:${port}${baseUrl}`,
+      });
+    });
+  });
+}
 
 export const formats = {
   'xlf': {
diff --git a/tests/legacy-cli/e2e/tests/misc/fallback.ts b/tests/legacy-cli/e2e/tests/misc/fallback.ts
index bb3b27b150bc..925d694a4800 100644
--- a/tests/legacy-cli/e2e/tests/misc/fallback.ts
+++ b/tests/legacy-cli/e2e/tests/misc/fallback.ts
@@ -12,7 +12,7 @@ export default function () {
   return (
     Promise.resolve()
       .then(() => ngServe())
-      .then(() => fetch('http://localhost:4200/', { headers: { 'Accept': 'text/html' } }))
+      .then((port) => fetch(`http://localhost:${port}/`, { headers: { 'Accept': 'text/html' } }))
       .then(async (response) => {
         assert.strictEqual(response.status, 200);
         assert.match(await response.text(), /<app-root><\/app-root>/);
@@ -27,7 +27,7 @@ export default function () {
         }),
       )
       .then(() => ngServe())
-      .then(() => fetch('http://localhost:4200/', { headers: { 'Accept': 'text/html' } }))
+      .then((port) => fetch(`http://localhost:${port}/`, { headers: { 'Accept': 'text/html' } }))
       .then(async (response) => {
         assert.strictEqual(response.status, 200);
         assert.match(await response.text(), /<app-root><\/app-root>/);
diff --git a/tests/legacy-cli/e2e/tests/misc/proxy-config.ts b/tests/legacy-cli/e2e/tests/misc/proxy-config.ts
index ff860a0a78ae..edc0619ad76c 100644
--- a/tests/legacy-cli/e2e/tests/misc/proxy-config.ts
+++ b/tests/legacy-cli/e2e/tests/misc/proxy-config.ts
@@ -34,7 +34,7 @@ export default function () {
   return Promise.resolve()
     .then(() => writeFile(proxyConfigFile, JSON.stringify(proxyConfig, null, 2)))
     .then(() => ngServe('--proxy-config', proxyConfigFile))
-    .then(() => fetch('http://localhost:4200/api/test'))
+    .then((port) => fetch(`http://localhost:${port}/api/test`))
     .then(async (response) => {
       assert.strictEqual(response.status, 200);
       assert.match(await response.text(), /TEST_API_RETURN/);
diff --git a/tests/legacy-cli/e2e/tests/misc/public-host.ts b/tests/legacy-cli/e2e/tests/misc/public-host.ts
index bf1e74448694..6b5aa3c52dfc 100644
--- a/tests/legacy-cli/e2e/tests/misc/public-host.ts
+++ b/tests/legacy-cli/e2e/tests/misc/public-host.ts
@@ -11,12 +11,12 @@ export default function () {
     .filter((ni) => ni?.family === 'IPv4' && !ni?.internal)
     .map((ni) => ni!.address)
     .shift();
-  const publicHost = `${firstLocalIp}:4200`;
+  const publicHost = `${firstLocalIp}`;
   const localAddress = `http://${publicHost}`;
 
   return Promise.resolve()
     .then(() => ngServe('--host=0.0.0.0', `--public-host=${publicHost}`))
-    .then(() => fetch(localAddress))
+    .then((port) => fetch(`${localAddress}:${port}`))
     .then((response) => response.text())
     .then((body) => {
       if (!body.match(/<app-root><\/app-root>/)) {
@@ -25,7 +25,7 @@ export default function () {
     })
     .then(() => killAllProcesses())
     .then(() => ngServe('--host=0.0.0.0', `--disable-host-check`))
-    .then(() => fetch(localAddress))
+    .then((port) => fetch(`${localAddress}:${port}`))
     .then((response) => response.text())
     .then((body) => {
       if (!body.match(/<app-root><\/app-root>/)) {
@@ -35,7 +35,7 @@ export default function () {
 
     .then(() => killAllProcesses())
     .then(() => ngServe('--host=0.0.0.0', `--public-host=${localAddress}`))
-    .then(() => fetch(localAddress))
+    .then((port) => fetch(`${localAddress}:${port}`))
     .then((response) => response.text())
     .then((body) => {
       if (!body.match(/<app-root><\/app-root>/)) {
@@ -44,7 +44,7 @@ export default function () {
     })
     .then(() => killAllProcesses())
     .then(() => ngServe('--host=0.0.0.0', `--public-host=${firstLocalIp}`))
-    .then(() => fetch(localAddress))
+    .then((port) => fetch(`${localAddress}:${port}`))
     .then((response) => response.text())
     .then((body) => {
       if (!body.match(/<app-root><\/app-root>/)) {
diff --git a/tests/legacy-cli/e2e/tests/misc/ssl-default.ts b/tests/legacy-cli/e2e/tests/misc/ssl-default.ts
index 0dd010337a60..c985df57b798 100644
--- a/tests/legacy-cli/e2e/tests/misc/ssl-default.ts
+++ b/tests/legacy-cli/e2e/tests/misc/ssl-default.ts
@@ -8,9 +8,9 @@ export default async function () {
   // TODO(architect): Delete this test. It is now in devkit/build-angular.
 
   try {
-    await ngServe('--ssl', 'true');
+    const port = await ngServe('--ssl', 'true');
 
-    const response = await fetch('https://localhost:4200/', {
+    const response = await fetch(`https://localhost:${port}/`, {
       agent: new Agent({ rejectUnauthorized: false }),
     });
 
diff --git a/tests/legacy-cli/e2e/tests/misc/ssl-with-cert.ts b/tests/legacy-cli/e2e/tests/misc/ssl-with-cert.ts
index 4ff12a5b2232..d1f107cd0e4e 100644
--- a/tests/legacy-cli/e2e/tests/misc/ssl-with-cert.ts
+++ b/tests/legacy-cli/e2e/tests/misc/ssl-with-cert.ts
@@ -9,7 +9,7 @@ export default async function () {
   // TODO(architect): Delete this test. It is now in devkit/build-angular.
 
   try {
-    await ngServe(
+    const port = await ngServe(
       '--ssl',
       'true',
       '--ssl-key',
@@ -18,7 +18,7 @@ export default async function () {
       assetDir('ssl/server.crt'),
     );
 
-    const response = await fetch('https://localhost:4200/', {
+    const response = await fetch(`https://localhost:${port}/`, {
       agent: new Agent({ rejectUnauthorized: false }),
     });
 
diff --git a/tests/legacy-cli/e2e/utils/network.ts b/tests/legacy-cli/e2e/utils/network.ts
new file mode 100644
index 000000000000..e7cff34eec9c
--- /dev/null
+++ b/tests/legacy-cli/e2e/utils/network.ts
@@ -0,0 +1,13 @@
+import { AddressInfo, createServer } from 'net';
+
+export function findFreePort() {
+  return new Promise<number>((resolve, reject) => {
+    const srv = createServer();
+    srv.once('listening', () => {
+      const port = (srv.address() as AddressInfo).port;
+      srv.close((e) => (e ? reject(e) : resolve(port)));
+    });
+    srv.once('error', (e) => srv.close(() => reject(e)));
+    srv.listen();
+  });
+}
diff --git a/tests/legacy-cli/e2e/utils/project.ts b/tests/legacy-cli/e2e/utils/project.ts
index f55194f3b8aa..3f750464dd3e 100644
--- a/tests/legacy-cli/e2e/utils/project.ts
+++ b/tests/legacy-cli/e2e/utils/project.ts
@@ -6,6 +6,7 @@ import { packages } from '../../../../lib/packages';
 import { getGlobalVariable } from './env';
 import { prependToFile, readFile, replaceInFile, writeFile } from './fs';
 import { gitCommit } from './git';
+import { findFreePort } from './network';
 import { installWorkspacePackages } from './packages';
 import { exec, execAndWaitForOutputToMatch, git, ng } from './process';
 
@@ -23,8 +24,16 @@ export function updateTsConfig(fn: (json: any) => any | void) {
   return updateJsonFile('tsconfig.json', fn);
 }
 
-export function ngServe(...args: string[]) {
-  return execAndWaitForOutputToMatch('ng', ['serve', ...args], / Compiled successfully./);
+export async function ngServe(...args: string[]) {
+  const port = await findFreePort();
+
+  await execAndWaitForOutputToMatch(
+    'ng',
+    ['serve', '--port', String(port), ...args],
+    / Compiled successfully./,
+  );
+
+  return port;
 }
 export async function prepareProjectForE2e(name: string) {
   const argv: yargsParser.Arguments = getGlobalVariable('argv');
diff --git a/tests/legacy-cli/e2e_runner.ts b/tests/legacy-cli/e2e_runner.ts
index 5dab8c769449..1cbe21956ede 100644
--- a/tests/legacy-cli/e2e_runner.ts
+++ b/tests/legacy-cli/e2e_runner.ts
@@ -7,9 +7,9 @@ import * as path from 'path';
 import { getGlobalVariable, setGlobalVariable } from './e2e/utils/env';
 import { gitClean } from './e2e/utils/git';
 import { createNpmRegistry } from './e2e/utils/registry';
-import { AddressInfo, createServer } from 'net';
 import { launchTestProcess } from './e2e/utils/process';
 import { join } from 'path';
+import { findFreePort } from './e2e/utils/network';
 
 Error.stackTraceLimit = Infinity;
 
@@ -254,15 +254,3 @@ function printFooter(testName: string, type: 'setup' | 'initializer' | 'test', s
   console.log(colors.green(`Last ${type} took `) + colors.bold.blue('' + t) + colors.green('s...'));
   console.log('');
 }
-
-function findFreePort() {
-  return new Promise<number>((resolve, reject) => {
-    const srv = createServer();
-    srv.once('listening', () => {
-      const port = (srv.address() as AddressInfo).port;
-      srv.close((e) => (e ? reject(e) : resolve(port)));
-    });
-    srv.once('error', (e) => srv.close(() => reject(e)));
-    srv.listen();
-  });
-}