Quick answer: Rent Project Zomboid = dedicated instead of coop host, ports 16261/16262 UDP, 6–12 GB RAM.
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Frequently asked questions (FAQ)
Coop or dedicated?
Coop dies when the host leaves. Dedicated (SteamCMD 380870) is the 24/7 rental.
Which ports?
UDP 16261 and 16262. Both, or you sit on “connecting”.
How much RAM?
2–8 players: 6–8 GB. Heavy mods: 10–12 GB.