Friends can't join your game server? We'll fix it.
Server Doctor tests your server from the internet and pinpoints why friends can't connect: port forwarding, CGNAT, firewall, wrong IP, TCP vs UDP or version mismatch. Then it walks you through the fix.
Free · No login · Works with home-hosted and rented servers
/fixWhy can't my friends join?
We contact only the single public address you enter, once, the way a game client would. Inputs aren't stored. Privacy
From "can't connect" to playing in three steps
No access to your router or server needed. Server Doctor only looks from the outside, like your friends do.
Tell us the address
Pick your game and paste exactly what your friends type to join. Add your router and public IP if you can; that's how we spot CGNAT.
We test from the outside
Server Doctor contacts your server from the internet the way the game does: Minecraft ping, RakNet, Steam query, Terraria, QUIC.
Get the fix
See the most likely cause with a confidence level and plain-English steps for your exact setup. Same engine in Discord with /fix.
Built for the games friends actually host
Each game gets its own protocol check and fixes. Custom ports work too: type address:port.
Minecraft: Java Edition
25565/TCPMinecraft: Bedrock Edition
19132/UDPPalworld
8211/UDPValheim
2456/UDPRust
28015/UDPARK: Survival Ascended
7777/UDPTerraria / tModLoader
7777/TCPHytale
5520/UDPDefault ports shown. ARK and some Palworld servers ignore test packets, so "no reply" there is inconclusive.
Step-by-step guides: Minecraft Java · Minecraft Bedrock · Palworld · Valheim · Hytale · CGNAT
Questions, answered
Why can't my friends join my game server?
The most common causes are: the port isn't forwarded (or is forwarded with the wrong protocol, TCP vs UDP), a firewall is blocking the server, your internet provider uses CGNAT so port forwarding can't work, friends were given your local 192.168.x.x address instead of your public IP, or the game versions don't match. Server Doctor checks these for you.
How do I know if I'm behind CGNAT?
Compare the WAN/Internet IP on your router's status page with the IP a 'what is my IP' site shows. If they differ, or the router's WAN IP starts with 100.64-100.127, you're behind CGNAT and port forwarding can't work. Use a tunnel such as playit.gg, a VPN overlay, ask your ISP for a public IP, or rent a server.
Is Server Doctor free?
Yes. The Discord bot and the web checker are free. Some recommendations link to hosting companies; some of those links may be affiliate links, which are always disclosed.
Does Server Doctor need access to my server or router?
No. It only sends the same kind of 'are you there?' packet a game client sends, to the single address and port you give it, from the internet. It never logs in to anything and needs no passwords.
Which games are supported?
Minecraft Java, Minecraft Bedrock, Palworld, Valheim, Terraria, Rust, ARK: Survival Ascended and Hytale. For ARK and some Palworld servers a 'no reply' result is inconclusive because those servers ignore test packets.
My friends can't join, but it works when I join my own public IP from home. Or the reverse?
Joining your own public IP from inside your home often fails even when everything works (routers without 'hairpin NAT'). Use the local IP at home and have friends use the public IP. Test from a phone on mobile data.
What does the bot do in my Discord server?
It adds two slash commands: /setup (pick the right way to host your game) and /fix (diagnose join problems). Replies are only visible to the person who ran the command. It doesn't read your messages.
Put a server doctor in your Discord
Two slash commands: /fix to diagnose join problems and /setup to pick the right way to host. Replies are only visible to the person who asked.
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