Check if your Don't Starve Together server is online
A Don't Starve Together server is a cluster: several shards, a port each, and just one of them — the master — that answers queries.
Advertisement
The ports Don't Starve Together uses
A typical cluster has an overworld shard and a caves shard: two processes on two different UDP ports. Test the master shard's port. Querying the caves port times out even when the whole cluster is healthy, and that is what usually lies behind a puzzling result here.
Advertisement
Still offline? Try this
Test the master shard's port specifically. If it answers and people still cannot get in, check that both shards actually started — when the caves shard fails to launch, the cluster accepts connections and then breaks the moment someone heads underground.