Hello.
Is the other network you have tired by the same ISP as your main network? As if they are by the same ISP the issue could still occur on a different network.
If it occurs on another network by another ISP, can you try to do a traceroute towards one of the servers you are trying to connect to and post results here?
https://learn.microsoft.com/en-gb/windows-server/administration/windows-commands/tracert

Hello.

The other network I tried belongs to a different carrier; I ran a traceroute to a random community server that I can't connect to. My network is the first one shown in the screenshot.

Could you try to contact your ISP with these findings? clearly there is an issue

Hello.
I reported the problem to my internet provider; they say the readings are normal and there are no active blocks regarding server connections, so the issue lies with the game itself.

Unfortunately we cannot exactly say from the error code where the problem lies.
You could try the following suggestions:

DayZ / BattlEye version mismatch after a patch — client not updated, or BE not installed/blocked. Verify game files, reinstall BattlEye  - if it started after a recent update

1. CGNAT — hop 2 is 10.199.64.1, so the user is behind MEO carrier-grade NAT. This frequently breaks the UDP query/connect handshake and Steam's server browser. Ask them to request a public IPv4 from MEO, or test on a phone hotspot — if it works on hotspot, it's the ISP/CGNAT.

2. Firewall / AV / VPN blocking UDP 2302–2305 and 27016 outbound.

3. Steam client issue — Steam must be running and logged in; corrupted download cache or a bad Steam download region will break server queries. steam://flushconfig.