[oCIS] after login, they were logged off for safety reasons

Hi there,
i followed the tutorial “Small-Scale with systemd” with nginx.
When i log in as admin, i get logged out right away because of security reasons.

I find this in the logfile of oCIS.

{"level":"error","service":"proxy","error":"Get \"https://owncloud-01.xxxxx.com/.well-known/openid-configuration\": context deadline exceeded (Client.Timeout
 exceeded while awaiting headers)","time":"2023-01-13T10:50:45.941786898+01:00","message":"could not initialize oidcAuth provider"}
{"level":"error","service":"proxy","error":"Get \"https://owncloud-01.xxxxx.com/.well-known/openid-configuration\": context deadline exceeded (Client.Timeout
 exceeded while awaiting headers)","time":"2023-01-13T10:50:56.146869417+01:00","message":"could not initialize oidcAuth provider"}

What am i doing wrong here, or what is missing in the tutorial ?

Thanks for any help.
Stefan