I'm currently connecting my upstairs desktop to the internet via Android USB tethering. Just the other day I decided to install a few home media servers for convenience while staying with parents.
I've tried Plex, Emby, Jellyfin, Kodi, a bunch of them. Every single time I try to access the server from other devices, while they can detect the server exists, they can't connect to it. To the other devices, my server is offline.
Now, after troubleshooting for a day and a half, it seems like I will have to either suck it up and accept a server via tethered connection isn't happening, or shell out for a PCIe or USB wireless adapter for the desktop. I've resisted buying a wireless adapter so far because I really don't NEEEEEEEEEEEEED it.
Double NAT is the problem. That explains why my desktop can access the rest of the devices on the network like the router fine, but my devices can't see my desktop at all. Lame.
My only non-fork-out-money solution that still uses the same setup seems to be a proxy server but at that point I doubt the connection will be good enough to justify doing it for a media server.
Time to use the downstairs desktop :)