Once your factory gets big, a specific multiplayer failure starts showing up: players time out while joining, or get dropped with Outgoing reliable buffer overflow. Often the host is completely fine and only other players are affected, which makes it feel random.
It usually is not random. Something in your save is too large to replicate to a joining client.
What the error actually means
Satisfactory replicates world state to each connecting client over a reliable channel with a finite buffer. If a single object needs to send more data than that buffer can hold, the send fails and the connection dies.
The classic trigger is one container holding an absurd number of item stacks. That happens more easily than you would think:
- Mass-dismantling storage containers. When you dismantle storage, the contents go into your personal storage box. Dismantle a whole storage array at once and that box ends up holding far more than it was ever designed to replicate.
- Any single inventory that has grown enormous over a long playthrough.
Because the host already has the state loaded locally, the host does not hit the same replication path. That is why "it works for me" is so common with this bug.
The fix
1. Clear out personal storage boxes. This is the first thing to check, and it resolves most cases. If you recently mass-dismantled storage, find the personal storage box that received it all and empty it, either by using the items, dumping them into properly sized storage, or discarding them.
2. If you cannot get in-game to fix it, a Satisfactory save editor can remove the offending personal storage box directly from the save file. Take a backup of the save before editing it, always.
3. Have every player set Network Quality to Ultra in their game settings. This affects how much data the client is willing to move and has resolved joining problems for a lot of people.
4. If you are running mods, the Satisfactory Modding team publishes a "Fix Reliable Buffer Overflow" mod specifically to mitigate the most common modded cause. Worth installing if your server is modded, since large content mods make this considerably more likely.
The other cause: slow loading, not overflow
There is a second, separate failure that looks similar: the client simply cannot send and process world data fast enough during the join, and times out. This gets progressively worse as your factory grows.
If that is what you are hitting:
- Ask affected players to lower graphics settings while joining.
- Players on a mechanical hard drive should move the game to an SSD, this makes a real difference on large saves.
- Temporarily removing mods narrows down whether a mod is the cause.
The distinction matters: overflow is a save content problem you fix on the server side, slow join is a client capability problem you fix on the player's side.
What this is not
Worth ruling out first, because the symptoms overlap and the fixes are completely different:
- Only some players can never connect at all, from the very first attempt. That is more likely a networking problem. Satisfactory needs both the game port (7777) and the Reliable Messaging port (8888) reachable, a requirement since Update 1.1. See our guide on Satisfactory server ports. On Space-Node both ports are provisioned automatically, so this is not something you configure yourself.
- Everyone gets dropped at the same moment, repeatedly. Look at server resources instead. If the server process is being killed rather than crashing, see exit code 137 and the Linux OOM killer.
Preventing it
- Do not mass-dismantle large storage arrays in one go. Empty containers before dismantling them.
- Keep an eye on your personal storage box, it is the usual dumping ground.
- Back up your save before big teardown or restructuring projects. Restoring a save from before the problem is usually faster than editing a broken one afterwards. Space-Node's panel has a Backups tab you can take manual backups from, and automatic off-site backups are available as an add-on if you would rather not remember to do it yourself.
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