the 192.168.65.1 address that manifested out of nowhere

Or it’s indeed the internal virtual lan your docker config uses…

Is that an actual problem or are you really just trying to fix the logs? That should be doable via headers so the real origin is preserved independent of proxying.

You’re gonna want to configure nginx to send along an X-Forwarded-For HTTP header (there’s also Forwarded, but it’s not as well supported yet). An example in a location block:

location / {
    proxy_pass http://backend/;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}

Looks like Jellyfin supports it.

In addition to configuring x-forwaded-for in NPM as suggested by others, you will also need to add 192.168.65.0/24 under Dashboard > Advanced > Networking > Known Proxies in Jellyfin.

https://docs.docker.com/desktop/features/networking/#how-containers-connect-to-the-internet
I think your discord friends are right.

Outbound traffic from the container is sent through Network Address Translation (NAT) using a virtual adapter (typically with an internal IP such as 192.168.65.3). You can view or change this with the Docker Desktop settings.

Draw a network map!!! It’s what I’ve done on every security engagement, ever. Mark out all your IP addresses, draw lines to denote the communicating RHP (random high port) against the well-known, e.g. 443/tcp HTTPs, for networks of hosts to servers. Then draw boxes around those IP spaces that are colocated on the same box. Then draw red lines perpendicular to every connection from a client to server that isn’t bounded on a single host.

The red lines denote non-localhost traffic - places to be observed, and for the most part the only IP:port assignments you should be relying on for routing.

My rec, draw the map and if that doesn’t help get back to us w it - or feel free to dm me.

Edit: I’ll find and post an example as a response this thread later.

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.

Just to understand better:

• When you say “when accessed from outside my home network”, what kind of access is that? Port forward? VPN?
• Is 192.168.1.1 your router?
• What’s your LAN netmask?
• NPM listens on 192.168.10.201 ports and Jellyfin/Komga on 192.168.10.202 ports?
• A connection from the outside comes through the router, gets forwarded to 192.168.10.201:443, the proxy sends it to 192.168.10.202:8096, and it shows up in the Jellyfin logs as coming from 192.168.65.1?

If all of the above is correct I would look at the network interfaces that are up on the mini-PC and the NAS, as well as inside the containers of the proxy and of Jellyfin, and see if there isn’t a 192.168.65.1 up on there somewhere for whatever reason.

You can also try making a manual request (wget, curl, nc) from the proxy container to Jellyfin and see what it shows up as.

May also want to see what’s the DNS situation in your LAN and on those machines. You mentioned “names” being used, how are those defined and resolved?

Last but not least are the containers you mentioned using docker bridge networks or ipvlan?