ARK servers are queryable with the standard A2S protocol, but the port layout catches almost everyone: the game port and the query port are unrelated numbers, not neighbours, and checking the wrong one makes a healthy server look offline.
Three ports, three jobs ¶
- Game port, conventionally 7777 UDP. Gameplay traffic. Not queryable.
- Peer port, conventionally 7778 UDP. Used internally by the engine; you generally do not touch it, and it must be free.
- Query port, conventionally 27015 UDP. This is the one A2S answers on, and the one to check.
Note the gap. In Rust the query port is one above the game port; in ARK it is a different range entirely. Point our checker at address:27015, not at 7777.
The server list is the least reliable signal ¶
ARK's in-game browser is well known for showing servers that are running as unavailable, and for hiding them behind filters that persist between sessions. A server missing from the list is weak evidence of anything.
Two things are worth trying before believing it. Use the favourites list with the address entered directly, which bypasses the browser's filtering. And check the query port from outside, which bypasses the list entirely. Between them you learn whether the server is running, which the browser does not reliably tell you.
Survival Ascended and Survival Evolved differ ¶
The two versions have separate servers, separate clients and separate ecosystems. A server address for one will not work with the other, and mods are not portable between them. When a server "stops working" shortly after someone updated something, confirm which version the client and the server are actually running before treating it as an outage.
Mods are the most common cause of a real outage ¶
Modded ARK servers fail in ways that vanilla ones do not, and the pattern is recognisable:
- A mod updates on the Steam Workshop, the server downloads it on restart, and it is incompatible with the current server build. The server crashes on start and never comes up.
- Client and server mod versions diverge, so the server is up and answering queries while your client refuses to join.
- A large modded server can take many minutes to start. During that window it answers nothing, and it is not down — it is loading.
That last one matters for monitoring: a check with an aggressive timeout during a scheduled restart reports an outage that never happened.
Reading the result ¶
- Query answers with a player count: up. If you cannot join, look at mods, version, password, or a full server.
- Query answers, list does not show it: the browser or the master list is at fault, not the server. Connect by favourite instead.
- No answer on 27015, and it is a fresh restart: give it several minutes before concluding anything.
- No answer at all, sustained: genuinely down, or the query port is not 27015.
For server owners ¶
- Forward 7777, 7778 and 27015 in UDP. Missing the query port produces a server that plays fine and cannot be found.
- Pin mod versions if the server is important to people. Auto-updating mods is the leading cause of unplanned ARK downtime.
- Set monitoring timeouts generously enough to survive a normal start. A modded server that takes six minutes to load will otherwise page you every restart, and alerts that cry wolf get muted.
Clusters multiply the failure surface ¶
ARK clusters link several servers so characters and creatures can transfer between them. Each is a separate process on its own ports, and any one can be down while the others run.
The symptom is specific and confusing: transfers fail, or a character is unavailable, while the server you are on works normally. Check every member of the cluster rather than the one you are connected to, because the one you are on is the one least likely to be the problem.
RCON is a separate port, and should not be public ¶
ARK exposes RCON on its own port, conventionally 27020, for administration. It is not a status port and should not be reachable from the internet: RCON access is complete control of the server. If your firewall rules were copied from a guide, check that 27020 is not among the ports forwarded.
Official versus unofficial servers ¶
Official ARK servers are Studio Wildcard infrastructure and behave differently from a server you or a host runs. They restart on a schedule you do not control, are taken down for maintenance without notice, and can be retired entirely. Querying one tells you whether it is answering right now, but there is nothing to fix at your end and no configuration to check.
For unofficial servers, everything in this article applies and the operator can act on it. Knowing which kind you are dealing with changes whether the answer is "wait" or "fix something".
Monitoring worth having ¶
Point a check at the query port, allow generously for a slow modded start, and require several consecutive failures before alerting. An ARK server that restarts nightly and takes six minutes to load will otherwise generate an alert every single night, and the one night it does not come back will look exactly like all the others.