Minecraft server status checker
A Minecraft server that players can join but that shows as offline here is almost always a port or address problem rather than a server problem — the game itself is running fine.
Which ports a Minecraft server needs
Java Edition speaks plain TCP, and this tool uses the same server-list ping your client sends when it draws the server in your multiplayer menu. If your address is a domain rather than an IP, an SRV record may be redirecting connections to a different port than the one you typed; the checker follows those records, so enter the address exactly as players do. Bedrock Edition is a different protocol on a different port and will not answer a Java query.
If it still shows offline
If the port test passes but the status query fails, the usual cause is `server-ip` being set in server.properties — bound to a specific interface, the server answers locally and ignores everything else. Leave it blank so it listens on all interfaces. If the port test fails too, the problem is upstream: a firewall rule, or your ISP putting you behind CGNAT so you have no reachable public address at all.