Connection issues are the most common launch-day complaint about Zombie Assault: Resurgence, and they hit co-op hardest. Two facts drive everything below: the game wants a constant connection for the whole session, and a disconnect ends the run — the mission cannot be resumed, so you requeue from Merc HQ. Co-op lag has a different shape from a disconnect. The clearest reported case is not your bandwidth at all, it is the host.

Check your platform first

  • Windows and macOS are the supported Steam platforms. Steam lists Linux as not supported.
  • A Linux install running the Windows build through Proton is outside the supported configuration, so connection or performance trouble there is not a setup the game supports.
  • Steam Deck support was promised for launch by the developers, and a Deck is a PC rather than a console release.

The full platform list, including the mobile builds, is on the cheats and platforms page.

The connection issues checklist

  1. Plan for an online-only session. Players asking whether the full game is playable offline have been told it will most likely require an internet connection, so the route to the servers has to stay stable for the whole run.
  2. Check the router, VPN or firewall for anything filtering game traffic. When the browser and ordinary downloads work fine, this is the usual culprit.
  3. Work out who it hit. A disconnect that took the whole squad points at the route; one that hit only you points at your own setup.
  4. Watch the minimap markers. In multiplayer, health and supply markers that fail to show, or arrive late, are the same fault showing up in the interface.
  5. Separate combat load from connection faults. Stuttering is worst in busier moments, and a shielder swarm is a heavy-combat situation rather than a networking one. When the frame rate itself is the problem rather than the session, that is a different half of the story — the performance and crash page has the ordered fix list.
  6. Keep the loadout prepared before you start. A disconnect costs you the run and the time spent in it.

What to do when a session drops

  1. Accept that the run is over. A disconnect ends the mission and there is no resume, so there is nothing to salvage from the session.
  2. Requeue from Merc HQ, the hub that handles matchmaking and where you vote for the next mission.
  3. Re-prepare your loadout before the next pull, since the previous one went down with the run.
  4. Escalate with details if it keeps happening. Ninja Kiwi's support portal is support.ninjakiwi.com, the email address is support@ninjakiwi.com, the official Discord is discord.gg/ninjakiwi, and r/zombieassaultofficial carries status posts.

Once you are back in the queue, the operations page covers how to pick the next mission and vote on the difficulty.

When the lag is on the host

The clearest reported case is host-side rather than bandwidth-side: teammates lag badly and eventually quit, while the host runs smoothly. The same player reports that even after quitting lobbies in which they were the host, the game made them host again — in the lobby somebody else has the star, but once the match starts it is them. Proton made no difference to the symptom.

  1. Check the lobby star before the mission starts. The player holding the star is the host.
  2. Make sure somebody else is hosting. In the reported case the game was unplayable for the other players whenever that player was the host.
  3. Check the host's platform too. A host running an unsupported Linux build is outside the supported matrix.
  4. Tell a client fault from a connection fault. If a session stutters for everyone rather than only for the other players, the cause sits on the client rather than the route.

How the lobby, the party and the host role work is covered on the co-op page.

When the drone gets stuck

This one gets confused with a connection problem, but it is a mission scripting issue. In the level 10 story mission the drone can get stuck: it tells you to leave it and find the objective, and when you come back the drone activates but does not move. The workaround is to quit and run the mission again, which worked for the player who hit it after roughly five attempts.

That mission and the rest of the campaign are on the story missions page.