I run a Plex server on in a Docker container on a Linux machine in my house on a Verizon FiOS internet connection. I’ve shared my library with many people and no one has a problem. Except one person who uses optimum.net as their service provider. When in their house I can’t direct connect to my Plex server, and everything gets sent through at 1mbps, I assume relayed through Plex.
I have a Tailscale mesh VPN setup for myself. I installed Tailscale on the “Chromecast with Google TV” Android app and connected it to my VPN. I set it up to route all traffic through the VPN using the same physical server that runs Plex as it’s Exit Node. When this is enabled, everything works fine.
What could be causing this. Another odd artifact of this set up - while connected to the optimum.net network I can’t even make simple HTTPS requests to a web server running in another Docker container on the same Linux machine as Plex. The request appears to never even make it to the server.
Sounds like a configuration problem on your friends end. Could be DNS blocking, or an aggressive firewall.
If it’s working over VPN, then the problem lies upstream. That tells you you CAN reach your server, so now you have to examine the other probable causes.