Port forwarding for a Terraria server
One TCP port. Terraria networks over a plain TCP stream: no query port, no second socket, and no UDP of any kind.
Your setup
Choose the firmware family rather than your exact model — every router in a family shares the same menus.
Out of the box it is 7777. If you changed that, use whatever you set in port in serverconfig.txt.
The local address of the computer that runs the server. Find it with ipconfig on Windows or ip addr on Linux; it will begin with 192.168, 10. or 172.
Open these
Your firmware takes ranges, so each line here is one rule.
- 7777 TCP
7777TCPGame trafficTerraria is TCP. A UDP rule here does nothing at all.
Do not open these
Good news: this game has no remote-admin port that could be exposed by mistake. Forward the ports on the left and stop there.
Step by step: your router
- 1
Give the server a fixed local IP
A forwarding rule targets a single local address. If the server comes back from a reboot with a new one, the rule quietly points at an empty address — which is how forwards seem to "break by themselves".
On this router:look for DHCP Reservation, Address Reservation, Static Lease or Manually Assigned IP
- 2
Open the router admin page
From a device on the same network, open one of these in a browser:
- 192.168.0.1
- 192.168.1.1
- 192.168.2.1
- 10.0.0.1
Almost always printed on a sticker on the router itself.
- 3
Find the port forwarding page
Port Forwarding, Virtual Server, NAT, Applications & Gaming, or Port Mapping
Vendors use at least six names for the same feature. Whatever it is called, the page you want is the one asking for a port, a protocol and a device on your network. If the external and internal port fields both exist, set them to the same number.
- 4
Create one rule per line
a description field, if there is one External / WAN / Public / Service port Internal / LAN / Private port Protocol Internal IP / Device / Server IP Terraria 7777 7777 TCP your server’s local IP Use the same number for the external and internal port. You can make the external one different, but then every player has to connect on that new number, so keep them identical unless you have a specific reason not to.
- 5
Let the server through its own firewall
The router is now sending traffic to the right computer, but that computer can still turn it away. Windows Defender Firewall is the usual offender: it blocks a newly installed dedicated server by default, and from outside that is indistinguishable from a broken forward.
Take it with you
Terraria — port forwarding rules -------------------------------- 7777 TCP -> <server local IP>
Check whether it worked
Always test from outside your network. A connection from another device in the house proves nothing: that traffic stays on your LAN and never passes through the rule you just created.
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The usual mistake
A UDP rule here achieves nothing — not a partial result, nothing. With so many games defaulting to UDP, it is easy to lose an evening confirming that a perfectly written rule is on the wrong protocol. A modded server such as tModLoader uses the same port, but the mod list must match on both ends before anyone can connect.
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Skipping port forwarding
A Terraria server is tiny, so hosting it elsewhere is about keeping the world available, not about speed. A world friends can drop into whenever they like is a different experience from one that needs arranging around whoever owns the host PC.