What your looking for is x-forwaded-for, that http tells an upstream server what the client IP is.

My guess is your docker network might be 192.168.68, there for the client IP you see is in that network.

I use nagios

I use pushover for everything alerting, from home assistant to nagios.

A 1 time payment and you get 10,000 alerts a month

Have you looked on here https://github.com/awesome-selfhosted/awesome-selfhosted

Have you looked at some like jellyfin?