Remote Connection Issue

[jamesking999898]

So I'm having an issue where I can't connect to my jellyfin server when I use remote home wifi networks, but can connect remotely through my mobile data. This seems to be a network issue cause my Plex, and my Wireguard VPN have the exact same issue. Im not sure how to diagnose this, furthest I've gotten is that it could be some DNS rebind issue?

My setup: running Jellyfin in a docker container on my ubuntu server. My router port forwarded 8096 to my server IP. My router is in a dmz from the ISP modem in order to avoid double NAT, ports show as open on port checker. So to clarify Internet -> ISP Modem -> DMZ -> Router -> Plex. I have no choice but to use both modem/router as separate network devices.

[TheDreadPirate]

Is your internet or the other person's home internet behind a CGNAT or something?

[jamesking999898]

Is your internet or the other person's home internet behind a CGNAT or something?

Nope, shouldn't be behind CGNAT. I am using a modem/router combo where its not in bridge mode, so maybe some DNS or double NAT problem I seriously dont know

[TheDreadPirate]

It has been a decade since I had a double router setup. IIRC, I had to port forward on the ISP router even though my own router was DMZ'd. I'm pretty sure I was port forwarding to my own router which then port forwarded to my server.

[jamesking999898]

So youre saying even though my router is in a DMZ, I need to port forward on the ISP modem? Thats kinda weird since DMZ should pass through all the traffic anyways. But I'll take a look at that and see.

The only other thing I can think of is some DNS issue with the ISP modem. Or some firewall stuff, unfortunately I dont have full access to the ISP modem as my dad controls it.