"Connection refused / unknown host / server not found" when a friend joins — why?

Messages like "connection refused," "unknown host," or "server not found" almost always mean the address is wrong or the server isn't up — not a firewall problem on a hosted server. Working through a short checklist usually pinpoints it fast.

What the errors are telling you

"Unknown host / server not found" points at the address itself — a typo, a missing port, or DNS that isn't ready. "Connection refused" usually means the server is offline or still starting.

Check in order

1. Is the server Online in the client area? If not, start it and wait for it to finish loading.
2. Is your friend using the exact IP:port from the Console, or your working domain?
3. Does their Minecraft version match the server's version?
4. If you use a domain, has DNS propagated (check DNSChecker.org)?

Warning: "Unknown host / server not found" points at the address (typo, missing port, DNS not ready); "connection refused" usually means the server is offline or still starting. Reading which message you get narrows it down quickly.

Frequently asked questions

It works for me but not my friend. See the "I can connect but friends can't" article — that's a client-side difference, not a server fault.