Troubleshooting

Start with /sg doctor: it checks arenas, storage, proxy forwarding, the network and the server name, and says in plain words what is wrong. Run it in game on a network so it can ask the proxy too.

Problem	Fix
Players can't join an arena	/sg list: full, resetting, being edited or its world isn't loaded. Admins with survivalgames.admin aren't put in arenas on servers without a lobby world.
The lobby blocks everything, even for ops	That's lobby.rules; give survivalgames.bypass to builders or set lobby.protect: false.
Network: players come back to the hub at once	The arena was full or not joinable; /sg doctor on the game server. Check spigot.yml settings.bungeecord: true.
Network: arenas missing from the hub menu	Same network.backend and database / Redis on every server and the hub; /sg network.
A server crashes with OutOfMemoryError	Each arena is a world: about 1.5 GB for four arenas.
Bedrock players get chest menus, not forms	Install Floodgate next to Geyser, and EranoAPI 1.0.0-alpha.4 or newer.
Console: Failed to read field (block_ticks=...), No key p	The map was saved by Minecraft 1.8 and has old scheduled block updates; newer versions drop them while loading it, with this message. Harmless.
Coins don't match my economy plugin	economy.provider: AUTO uses Vault only when Vault and an economy plugin are installed.