Host Lobby Becomes Unjoinable After Network Reconnection

Status:	Pending Moderation
Priority:	Critical
Added by:	oddynz on October 27, '26
Assigned to:	Unassigned
Due date:
Reported for:	S06.04

Steps to Reproduce

1. Player A hosts (sitting in the Space Rig is enough).
2. Player B joins through Steam (Join Game or invite). It works.
3. Turn off Player A's (host's) Wi-Fi for about 10 seconds, then turn it back on. Wait about 20 s for Steam to reconnect.
4. Player B is dropped ("Your connection to the host has been lost").
5. Player B tries to rejoin through Steam Join Game or an invite: "Multiplayer session has ended". This repeats on every attempt.
6. Player A starts a mission, then aborts back to the Space Rig. Player B still can't join.
7. Player A quits and relaunches DRG. Player B joins straight away.

Explanation

Same bug as #427 ("Session becomes unjoinable after network error and restoration"), with logs, extra findings and a workaround.

When the HOST's Steam client loses its connection to Steam's servers and reconnects (Wi-Fi drop, router blip, or a Steam server disconnect), the host's lobby becomes permanently unjoinable. Friends who try to join through Steam (Join Game or an invite) get "Multiplayer session has ended", or nothing happens at all.

Starting a mission, or aborting the mission back to the Space Rig, does NOT fix it. Quitting and relaunching DRG on the host fixes it every time; restarting Steam alone doesn't.

Expected: friends can rejoin once the host's connection recovers (or DRG recreates the lobby automatically).
Actual: the session is unjoinable until the host restarts the game.

It happens on any host. Reproduced 3 times on Steam build 158958 (Oct 2026): Steam Deck host (SteamOS Game Mode, Wi-Fi) and Windows 11 PC host (Wi-Fi), with Windows 11 PC clients on the same home network. Steam Decks hit it most, because they reconnect to Steam several times a day, so it often looks like "friends can't join my Steam Deck".

It doesn't need a game disconnect. The host's Steam reconnecting is enough, even while hosting alone in the Space Rig. On the host, right after the reconnect, every lobby update fails, every 30 s, indefinitely (473 failures over 4 hours in one log):
LogOnline: Warning: OSS: Async task 'FOnlineAsyncTaskSteamUpdateLobby bWasSuccessful: 0 Session: GameSession' failed
On the joining client:
FOnlineAsyncTaskSteamJoinLobby bWasSuccessful: 0 ... Result: '2' k_EChatRoomEnterResponseDoesntExist
LogOnline: Error: FSD Join Session - Failed, reason 5
or, hours later:
STEAM: Did not find required keys for lobby KeysFound=0 HostKeysFound=0 SteamAddrKeysFound=0
Invite accept returned no search result.
The host's Steam keeps advertising the old lobby ID, which no longer exists. DRG never creates a new lobby until it's restarted.

Logs attached:
A1/A2: Steam Deck host log + its Steam connection log (Steam reconnect at 06:35:48 UTC, then 473 UpdateLobby failures)
A3: client failing to join that dead lobby (KeysFound=0)
B1: client log, Deck host's Wi-Fi toggled at 11:39:55 UTC (DoesntExist / reason 5, x5)
C1/C2: Windows PC host log + its Steam connection log (Wi-Fi toggled at 12:02:13 UTC, UpdateLobby failure at 12:02:54)

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