Terraria connection trouble is usually the port, or — on tModLoader — a version/mod mismatch. Here's the fix for both, plus password and player-limit issues that get mistaken for connection failures.
Quick answer
Terraria "can't connect" is usually a closed port or, on tModLoader, a version or mod mismatch. Open TCP port 7777 on the server, join through Multiplayer → Join via IP with the exact IP and port, and make sure your game version matches the server's. On tModLoader, use the same tModLoader version and enable the server's mods.
Open the port
Terraria uses a single TCP port by default:
7777/tcp game (default)Join the right way
In Terraria → Multiplayer → Join via IP, enter the server IP and port 7777. Make sure your game version exactly matches the server's — a vanilla client can't join a tModLoader server and vice-versa.
tModLoader: match versions and mods
For a modded (tModLoader) server, the client must run the same tModLoader version and have the server's mods enabled. Subscribe to the server's mod list and enable them before joining.
A common mistake: trying to join a tModLoader server from vanilla Terraria (or the wrong tModLoader branch). Launch the matching client.
Vanilla vs tModLoader — which client to use
Most "can't connect" reports on modded servers come down to a client/server type mismatch. They are not interchangeable:
| Server type | Client to launch | Mods needed? |
|---|---|---|
| Vanilla Terraria | Vanilla Terraria, same game version | No |
| tModLoader | tModLoader, same loader version | Yes — the server's exact mod list, enabled |
| TShock (vanilla-compatible) | Vanilla Terraria, same game version | No (server-side plugins only) |
Open 7777/tcp, Join via IP, and for tModLoader match the loader version and enable the server's mods.
Quick diagnostic
- Confirm you launched the matching client from the table above — this is the single biggest cause.
- For tModLoader, check the loader version matches and the server's mods are enabled, not just subscribed.
- Try Join via IP with the explicit port
server-ip:7777. - If it still fails, rule out a password typo or a full server before blaming the network.
- Confirm the host firewall allows 7777, not just the router forward.
Other reasons "can't connect" happens
- The server has a password set and it's wrong or wasn't entered — Terraria's error for this can look like a generic connection failure.
- The server is full — check
MaxPlayersin serverconfig.txt against how many are already connected. - The host's OS firewall blocks 7777 even though the router forwards it.
- TShock or another server plugin is misconfigured and rejecting connections at the plugin layer, not the network layer.
How to prevent it
- Publish the exact Terraria/tModLoader version and mod list with your server so players don't guess.
- Keep serverconfig.txt backed up before editing so a bad change is easy to revert.
- Update the server the same day as a Terraria/tModLoader update to avoid an extended version mismatch window.
Related errors
For the general port-forwarding steps, see how to port forward a game server. If the connection drops after joining rather than failing to start, see fixing "connection timed out" on game servers.
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