Angular end-to-end tests on random port - protractor

Question

We are running angular e2e tests on a CI environment where tests are run at the same time on the same build slave (for example for different branches).
Since our recent upgrade to angular 7 (from angular 5) protractor uses the default port (4200).
CI jobs now occasionally are failing because port 4200 is in use.
I found the option to run with port 0:
ng e2e --port 0
This does seem to use a random port, but the tests fail, see below.
I tried on a clean new angular project created with angular cli, no changes.
ng e2e
works fine
How can I get the e2e tests to run without port number clashes?
Angular CLI: 7.1.0
node: v8.9.3
OS: Windows 10 Version 1607
Thanks in advance,
Rob
This output is from the failing run:
$ ng e2e --port 0
** Angular Live Development Server is listening on localhost:49152, open your browser on http://localhost:49152/ **
Date: 2018-12-03T15:16:48.890Z
Hash: 97006afaee956149f40f
Time: 7337ms
chunk {main} main.js, main.js.map (main) 9.77 kB [initial] [rendered]
chunk {polyfills} polyfills.js, polyfills.js.map (polyfills) 223 kB [initial] [rendered]
chunk {runtime} runtime.js, runtime.js.map (runtime) 6.08 kB [entry] [rendered]
chunk {styles} styles.js, styles.js.map (styles) 16.3 kB [initial] [rendered]
chunk {vendor} vendor.js, vendor.js.map (vendor) 3.43 MB [initial] [rendered]
i ｢wdm｣: Compiled successfully.
[16:16:49] I/update - chromedriver: file exists C:\Users\rob.gansevles\tmp\noot\node_modules\protractor\node_modules\webdriver-manager\selenium\chromedriver_2.44.zip
[16:16:49] I/update - chromedriver: unzipping chromedriver_2.44.zip
[16:16:49] I/update - chromedriver: chromedriver_2.44.exe up to date
[16:16:50] I/launcher - Running 1 instances of WebDriver
[16:16:50] I/direct - Using ChromeDriver directly...
DevTools listening on ws://127.0.0.1:50805/devtools/browser/7ee01341-be32-4d52-ae53-0794c11c8864
Jasmine started
[23540:12920:1203/161652.814:ERROR:tcp_socket_win.cc(861)] connect failed: 10049
[23540:12920:1203/161652.814:ERROR:tcp_socket_win.cc(861)] connect failed: 10049
[23540:12920:1203/161652.823:ERROR:tcp_socket_win.cc(861)] connect failed: 10049
[23540:12920:1203/161652.823:ERROR:tcp_socket_win.cc(861)] connect failed: 10049
[16:17:03] E/protractor - Could not find Angular on page http://localhost:0/ : retries looking for angular exceeded
workspace-project App
× should display welcome message
- Failed: Angular could not be found on the page http://localhost:0/. If this is not an Angular application, you may need to turn off waiting for Angular.
Please see
https://github.com/angular/protractor/blob/master/docs/timeouts.md#waiting-for-angular-on-page-load
Please see
https://github.com/angular/protractor/blob/master/docs/timeouts.md#waiting-for-angular-on-page-load
at executeAsyncScript_.then (C:\Users\rob.gansevles\tmp\noot\node_modules\protractor\built\browser.js:720:27)
at ManagedPromise.invokeCallback_ (C:\Users\rob.gansevles\tmp\noot\node_modules\selenium-webdriver\lib\promise.js:1376:14)
at TaskQueue.execute_ (C:\Users\rob.gansevles\tmp\noot\node_modules\selenium-webdriver\lib\promise.js:3084:14)
at TaskQueue.executeNext_ (C:\Users\rob.gansevles\tmp\noot\node_modules\selenium-webdriver\lib\promise.js:3067:27)
at asyncRun (C:\Users\rob.gansevles\tmp\noot\node_modules\selenium-webdriver\lib\promise.js:2927:27)
at C:\Users\rob.gansevles\tmp\noot\node_modules\selenium-webdriver\lib\promise.js:668:7
at
at process._tickCallback (internal/process/next_tick.js:188:7)
From: Task: Run it("should display welcome message") in control flow
at ControlFlow.emit (C:\Users\rob.gansevles\tmp\noot\node_modules\selenium-webdriver\lib\events.js:62:21)
at ControlFlow.shutdown_ (C:\Users\rob.gansevles\tmp\noot\node_modules\selenium-webdriver\lib\promise.js:2674:10)
at shutdownTask_.MicroTask (C:\Users\rob.gansevles\tmp\noot\node_modules\selenium-webdriver\lib\promise.js:2599:53)
From asynchronous test:
Error
at Suite. (C:\Users\rob.gansevles\tmp\noot\e2e\src\app.e2e-spec.ts:10:3)
at Object. (C:\Users\rob.gansevles\tmp\noot\e2e\src\app.e2e-spec.ts:3:1)
at Module._compile (module.js:635:30)
at Module.m._compile (C:\Users\rob.gansevles\tmp\noot\node_modules\ts-node\src\index.ts:439:23)
at Module._extensions..js (module.js:646:10)
at Object.require.extensions.(anonymous function) [as .ts] (C:\Users\rob.gansevles\tmp\noot\node_modules\ts-node\src\index.ts:442:12)
Failures *
1) workspace-project App should display welcome message
- Failed: Angular could not be found on the page http://localhost:0/. If this is not an Angular application, you may need to turn off waiting for Angular.
Please see
https://github.com/angular/protractor/blob/master/docs/timeouts.md#waiting-for-angular-on-page-load
Executed 1 of 1 spec (1 FAILED) in 10 secs.
[16:17:03] I/launcher - 0 instance(s) of WebDriver still running
[16:17:03] I/launcher - chrome #01 failed 1 test(s)
[16:17:03] I/launcher - overall: 1 failed spec(s)
[16:17:03] E/launcher - Process exited with error code 1
An unexpected error occurred: undefined
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command