Custom sync server - Anki does not initiate

Anki Syncing & AnkiWeb
1

I built a docker sync server using these directions: anki/docs/syncserver at main · ankitects/anki · GitHub

When I try to start Anki with SYNC_USER1=user:pass anki --syncserver Anki does not start and I must press Ctrl + C

Anki starting…
2024-11-16T10:57:50.888891Z INFO listening addr=0.0.0.0:8080
^CTraceback (most recent call last):
File “anki.syncserver”, line 14, in run_sync_server
File “anki._backend”, line 93, in syncserver
Exception

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File “”, line 1, in
File “aqt”, line 38, in
File “anki.syncserver”, line 14, in run_sync_server
KeyboardInterrupt

If I set https://localhost::8080/ under Self-hosted sync server option I receive this warning: Invalid sync server specified. Please check the preferences.