[0.18.17] Error trying to connect to MP server Invalid packet (type ServerToClientHeartbeat) with 10G Nic

[djnono]

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)

bug_connection_error.zip

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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.

[djnono]

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 ?

[ckreon]

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).

[djnono]

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