Compatibility Report

• Name of the game with compatibility issues: No Man's Sky
• Steam AppID of the game: 275850

System Information

• GPU:
• Driver/LLVM version: nvidia 440.82
• Kernel version: 5.4.44-1-MANJARO
• Link to full system information report as Gist: https://gist.github.com/JPLeBreton/27ee957c57ea36298312ca3a09eadd70
• Proton version: 5.0-9

I confirm:

• [X] that I haven't found an existing compatibility report for this game.
• [x] that I have checked whether there are updates for my system available.

steam-275850.log

Symptoms

Can't play multiplayer since the game's Cross Play Update last month. The older release version of Proton, 4.11-13, doesn't seem to have this issue.
Note that I can still connect to the game's "discovery services", ie the server that lets players log and see each other's discovered planets, bases, etc, just fine. I believe that's a whole separate kind of network access.

Reproduction

1. Launch the latest version of the game (2.60) with Proton 5.0-9.
2. Load a savegame.
3. Enter the options menu, and select the "network" section.
4. Observe: a box pops up that says "No connection to matchmaking services".
5. Quit the game and set it to run using Proton 4.11-13 instead.
6. Relaunch the game, load a save and enter the same options menu.
7. Observe: networking error doesn't occur as before.

Expected behavior: Multiplayer works with all versions of Proton.