"Server not responding" constantly for only local user

[psiphre]

I am having a weird issue with a server that i'm running for myself and a friend.

it's running on a separate computer from mine. i've got my router forwarding port 34197 to the computer that is running the factorio server.

my friend who is playing from a different city will connect, play, no lag, no interruptions, no problem.

when I connect from my computer on the same network segment, it always takes two tries to connect to the server. this is true whether i use the server's local ip address or my DNS address. the first attempt fails with the error "Couldn't establish network communication with server", the second attempt is successful.
i also experience the game pausing frequently to display a bar informing me "server is not responding". it goes away in a few seconds.
additionally, periodically while i'm playing my input will pause (if i am running, i will stop in place but my character will have a leg raised like he is about to take a step) for 2-3 seconds and then resume with no "server is not responding" message.

i've tested this with a second, notebook pc which is far less powerful than my desktop. when i connect to the server using this notebook from outside my network, i have no issues with "server not responding" even on a very small pipe (less than 1mbps).
when i connect to the server using this notebook from inside my network, i get the same "server not responding" and input halting issues.

i believe this rules out my desktop pc as the issue. and it shouldn't be the router that is an issue because my friend doesn't experience these problems.

so what could cause these issues between a computer and another computer on the same network segment?

i've attached a log of pings from my pc to the server as well as the factorio-current.log from my desktop pc. i started the ping, then connected to the server (requiring two attempts), then played until i got a "server not responding" window.

factorioping.txt

factorio log from

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i also have the factorio-current.log from my desktop PC.

factorio-current.log

a ping from my pc to the pc running the server on my local network

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[Loewchen]

Post complementary logs of server and client after experiencing the issue please. If you start a pure LAN game on your server, do you experience the issue on the client as well? You could completely rule out the router if you had a different router or even just a switch to test it on.

[psiphre]

i've been playing this morning with my friend - here are two logs, one from the server, one from my pc.

i'm not completely sure what you mean by "start a pure LAN game on the server" and i don't know how i would go about running another instance with the current game running.

server log:

factorio-current-server.log

server log

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client log:

factorio-current.log

client log

(292.33 KiB) Downloaded 116 times

[psiphre]

I solved the issue. factorio traffic to other hosts on the local network was trying to go out a second interface that's used for SAN traffic. i spun up a different vm to host the factorio server and now all is well.