🎮 Game Error Codes What it means & how to fix it

R.E.P.O. Can't Join Lobby? Here's the Fix

R.E.P.O. runs on Steam peer-to-peer with the host acting as server, so most 'can't join lobby' errors are the host's firewall/NAT or a version mismatch after an update — not Semiwork's servers. Fastest fix: both players update to the same build, the host allows the game through the firewall, and you rejoin via the Steam friends list.

Exact details for R.E.P.O.

Network model
Steam peer-to-peer (host = server)
Max players
6
Host must allow
R.E.P.O. + Steam through firewall
First check
Both players on same version

Error codes

Lobby not showing / can't see friend's game Steam friends presence isn't exposing the host's lobby to you

Cause: Steam friends-only privacy, mismatched builds, or Steam presence not refreshed.

Fix:
  1. Both players update R.E.P.O. to the exact same version.
  2. Host sets lobby to Friends or Public, not Private/Invite-only.
  3. Join through Steam > Friends > Join Game rather than the in-game browser.
  4. Restart Steam so friends presence refreshes.
Connecting to lobby then timeout P2P handshake to the host failed

Cause: Host's strict NAT / firewall blocking the incoming peer connection.

Fix:
  1. Host allows R.E.P.O. and Steam through Windows Firewall (Private + Public).
  2. Host enables UPnP on the router or sets NAT to Open.
  3. Both disable VPN so the P2P route isn't broken.
  4. Host uses a wired connection to stabilise the session.
Version mismatch / failed to join Client and host builds differ

Cause: One player updated after a patch and the other didn't.

Fix:
  1. Verify game files in Steam for both players.
  2. Opt out of any beta branch unless both use it.
  3. Restart Steam to force the update to apply.
  4. Rejoin only after both show the same version number.

Fixes that work for most R.E.P.O. errors

  1. Match versions: both players on the exact same build.
  2. Host allows R.E.P.O. + Steam through the firewall.
  3. Host enables UPnP / Open NAT for incoming P2P.
  4. Join via Steam friends list, not in-game browser.
  5. Both disable VPN.
  6. Verify game files after any update.

FAQ

Why can't I join my friend's R.E.P.O. lobby?

Almost always a version mismatch or the host's firewall blocking the peer connection. Make sure both of you are on the same build, have the host allow R.E.P.O. through the firewall and enable UPnP, then join through the Steam friends list.

Does R.E.P.O. use dedicated servers?

No. R.E.P.O. is Steam peer-to-peer and the host machine acts as the server, so connection issues come from the host's network (NAT/firewall) rather than a central server.

How many players can join a R.E.P.O. lobby?

Up to 6 players in online co-op. If the lobby is full or set to invite-only you won't be able to join until the host opens a slot or changes lobby privacy.

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