Slay the Spire 2 Connection Timed Out: Who's Stopping You from Playing with Friends

You might think Slay the Spire 2 uses P2P networking and is therefore more stable than server-based connections, but in reality it carries the risk of being unable to connect to friends, failing to join rooms, or disconnecting mid-game, and all you see is “Connection timed out.” This is related to the host’s network stability, each player’s network openness, and the game files themselves, so we need to troubleshoot and resolve these issues one by one. This article will discuss that problem.

Confirm Each Player's Status Before Troubleshooting

💡Please note that NAT type and the use of mods are things many players overlook.

Quick steps to check NAT status (for Windows 11):

1. Press Win+X and choose Terminal (Administrator)
2. Enter the command: netsh interface Teredo show state
3. Check the NAT type shown above.

Note: Most players will see Restricted or Moderate, which is commonly referred to as NAT2. This is normal, standard P2P multiplayer should work fine, so there’s no need to force Cone/Open.

Why Is Everyone in the Room Important?

Three players can connect normally while the fourth player cannot join no matter what, or after the host connects with the fourth player the other players cannot join. This is something many Slay the Spire 2 players have encountered. This is the nature of P2P games: each player can affect the entire lobby.

So we recommend that before starting an official game you confirm which player is best suited to act as the host, ensure every player's network status is set to open, and, if necessary, repair your game files:

1. Close the game and exit Steam on every PC.
2. Restart Steam. The original host creates a new lobby and sends fresh invitations.
3. If nobody can join, try a different host. A player who can join but cannot host may have firewall, router, or network issues on their end.
4. If a new host still fails, create a new multiplayer save as a test. If the fresh save works, the original session is the problem.
5. If nothing connects, verify game files in Steam (right-click > Properties > Installed Files > Verify integrity of game files) and restart with unnecessary software closed. Keep Steam Overlay enabled for invitations.

Next, we need to address players' network issues, whether you're the host or a client.

Fix Your Local Network Issues

Check Your Firewall and Security Software

If you can't invite or join a friend's lobby, start by checking your security software. Windows Defender Firewall or a third-party antivirus may be blocking Steam or Slay the Spire 2 from communicating properly.

Make sure both Steam and Slay the Spire 2 are allowed through your firewall. If you're using additional security software, check its allow list as well. You can temporarily pause protection to test whether it's causing the problem, but turn it back on immediately afterward. If the connection works, create a permanent exception instead of leaving your PC unprotected.

Disable VPNs and Other Network Routing Tools

VPNs, proxies, and routing tools can interfere with Steam's multiplayer connections, even if they work fine for web browsing or other online games.

For troubleshooting, disable any VPN, proxy, or Cloudflare WARP and try connecting again. If you use more than one networking tool, turn them all off for the first test. Once you confirm the game works normally, you can enable them again one by one to identify the cause.

Improve Connection Stability

A stable connection is just as important as a fast one. Even brief network interruptions can prevent you from joining a friend's lobby or cause someone to disconnect during the session.

If possible, switch to a wired Ethernet connection while testing. If you're on Wi-Fi, move closer to your router and pause large downloads, cloud backups, or video uploads on your network. These activities can briefly interrupt the connection, even if websites and voice chat continue to work normally.

When GearUP Is Worth Testing?

GearUP is a game network optimization tool known to many players. It is recommended as a last-resort optimization because if your local network is fine, the issue is likely with the public network connection, and changing DNS or using proxy tools cannot precisely adjust the data transmission path.

GearUP only handles game traffic and can build dedicated tunnels based on the actual P2P connection situation, so it can improve performance in multiplayer sessions. It reduces the number of network configuration steps and can also lessen network jitter during multiplayer, making connections relatively more stable. You can:

1. Launch GearUP and search for Slay the Spire 2, then click boost.
2. Wait for GearUP’s automatic optimization, then start the game, and please do not close GearUP, otherwise the optimization will stop.
   

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If just one person has a network issue, does that stop everyone from connecting?
Not necessarily. Players with good networks can still connect. In this situation, usually only the player with the poor connection cannot join the room, while the other players can play normally.

If my NAT type is Strict, does that mean I can't connect?
Not necessarily. Strict only means the chance of a successful connection is low, not impossible. However, even if you manage to connect to the host, it may prevent other players from connecting, because Slay the Spire 2 requires each player to exchange data with every other player.

What should you do first when a connection times out?
Don't rush to change the host. First confirm that every member's network status is good, then try switching the host among different players to find the most stable connection.