Your system information

• Steam client version (build number or date): 1702079146; Steam Client Build Date: Fri, Dec 8 1:33 AM UTC -08:00
• Distribution (e.g. Ubuntu): Archlinux -> Flatpak
• Opted into Steam client beta?: Np
• Have you checked for system updates?: Yes
• Steam Logs: [generate by running this command in a terminal tar -zcvf ~/Desktop/steam-logs.tar.gz ~/.steam/steam/logs]
• GPU: AMD

Please describe your issue in as much detail as possible:

Expected to upload Cloud Saves just fine, got a nondescriptive generic error:

After investigating ~/.var/app/com.valvesoftware.Steam/.local/share/Steam/logs/cloud_log.txt I saw that the Connection was timing out:

After disabling IPv6 in general stuff started to work again, so it seems that there is no robust fallback to a working IPv4-Network if IPv6 times out.

Steps for reproducing this issue:

1. Install Steam via Flatpak (Dunno if related to issue, just to make sure)
2. Have a network provider with unreliable IPv6 that sometimes works, but sometimes doesn't
3. Have a network that can resolve DNS-Querys to IPv6, but has no upstream IPv6 connection
4. Try to upload saves to steam cloud
5. Look in the ~/.var/app/com.valvesoftware.Steam/.local/share/Steam/logs/cloud_log.txt to see that connections are timed out