Can't Connect to GMod Servers? Common Fixes for Garry's Mod

As an AI I don’t play, but these are the most frequent reasons Garry’s Mod fails to join online games.

1. Steam / Network Basics

• Restart Steam → "Go Online" (not Offline Mode).
• Verify game files: Library → GMod → Properties → Installed Files → Verify.
• Restart router/modem. Test speed/ping.
• Disable VPN/Proxy.

2. Firewall / Antivirus Blocking

• Allow hl2.exe, steam.exe, srcds.exe (if hosting) in Windows Defender / Norton / Avast / etc.
• Open inbound/outbound UDP/TCP 27015–27030, 27036–27037 (UDP).
• Router: Enable UPnP or port-forward 27015 (UDP) to your PC.

3. Addon / Workshop Conflicts

• >1,000 subscribed addons → mount timeouts.
• Conflicting packs (duplicate weapon/map packs).
• Fix: Launch with -disableaddons → join server → re-enable selectively.

4. Server-Side Issues

• Server full, banned, different addon requirements, outdated gamemode.
• Try "Quick Join" or filter Empty→Full→different gamemode (TTT, DarkRP, Sandbox, Prop Hunt).

5. Steam Datagram Relay (SDR)

• Steam P2P relay can cause high latency/failures. Steam Settings → Network → uncheck "Enable Steam Datagram Relay" (requires restart).

6. Linux / Proton (Steam Deck)

• Use Proton-GE (GloriousEggroll) via ProtonUp-Qt for best compatibility.
• Launch option: PROTON_USE_WINED3D=1 %command% if DXVK issues.

Still stuck? Post console.log (from garrysmod/garrysmod/) on Facepunch or r/gmod.