Factorio Forums

So, since a few days (weeks ?) I can't connect to some MP servers (others work perfectly)
The error in the log is Invalid packet (type ServerToClientHeartbeat) received from IP ADDR:({95.216.28.149:7010}): heartbeat sequence number (553786) outside latency window [552986, 553786)
The attached zip includes full log, network trace, and a wireshark connection of all transactions between me and the server during this attempt.
Server was ColonellWill's, Vanilla playthrough, no mods.
Same error with steam, or fresh install from factorio.com

I have a 10g fiber, and no issues with any other games, so I don't think it's on my side, but everyone else could connect without issues, so I'm not absolutely ruling it out.
I have a 55ms ping with the server, and a traceroute shows no abnormalities
A quick look at Wireshark trace indicates no packet or sequence errors

Tried several public MP servers, some work, some produce the same error.
Server log indicates nothing special either.

Second Test to isolate my network, I just tried from an old laptop, same network config (only difference being 1g copper instead of 10g sfp) and I can connect to the same server.
Also tested over wifi without issue.

So is it possible that the 10g network breaks factorio somehow ? buffer on the tx/rx queues ?

I want to echo that 10G NICs do indeed seem to break Factorio Multiplayer.

I was having Invalid Packet Type errors before swapping over to my 1G - all fixed.

I was troubleshooting with my laptop first, similar to you, wondering why it was connecting just fine, even if I used the same hard-line as my desktop. This explains that, to some degree.

It's still unclear what issues are arising with the 10G NIC - perhaps MTU related but that appears the same as the 1G NIC on my machine (1500).

the packet are all small in size, so I highly doubt it's MTU related. And since I can only play with the MTU on the client side, I can't really be definitive about it.

I've also confirmed that switching to a 1G nic solves the problem, with the exact same config, and that using a 10G nic on a pc which is known to work fine instantly breaks it, so there is definitively an issue with 10G nics.

I've only tested SFP+ Nics as this is what I have on hand, specifically an ASUS XG-C100CF and an Aquantia AQtion)

Marking it as a bug