Unable to play online, even with good connection

[Demon Of The Fall]

I play using my phone's mobile data as my internet connection (It's the only way I can play with low ping). I've been doing that for 4 months until 3 days ago, I could no longer do that. I can only connect using wifi (which for me causes too much ping, it's unplayable)

Here are some of the symptoms when I try to connect while using mobile data:

When I launch CnCNet Yuri's Revenge, it always displays "N/A" for the number of players online, and at the bottom left it says "Failed to check for updates".

When I try to connect, the lobby list is empty but the chat is working fine. 5 minutes later, the lobby starts showing games to join, but in any game that I join the map doesn't download for me, even when it's a map that I already have so I can't play anything.

Offline skirmish works fine. Internet is working fine. This happened so suddenly, I did not change anything. I tried re-installing the client but that didn't help. I've been on version 4.19 since it got out, and played it normally before this happened, so the problem isn't due to the software update.