Found an interesting issue with Better Alert Arrows.

For whatever reason, one person out of our group cannot connect to our dedicated mp server when that mod is enabled. Everyone else can connect just fine.

When I remove Better Alert Arrows, he can connect to the server again.

He's running Factorio through Steam on Win10 with latest updates (as far as I'm aware).

That's... interesting. What was the exact error your friend was getting?

"Cannot establish network communication with the server" or something like that. No other error massage.

Relevant snippet of factorio-current.log

25.550 Info UDPSocket.cpp:33: Opening socket
25.554 Info ClientMultiplayerManager.cpp:591: UpdateTick(4294967295) changing state from(Ready) to(Connecting)
35.818 Error ClientMultiplayerManager.cpp:100: MultiplayerManager failed: multiplayer.not-received-connection-accept-reply
35.818 Info ClientMultiplayerManager.cpp:591: UpdateTick(4294967295) changing state from(Connecting) to(InitializationFailed)
608.360 Info ClientMultiplayerManager.cpp:207: Quitting multiplayer connection.
608.360 Info ClientMultiplayerManager.cpp:591: UpdateTick(4294967295) changing state from(InitializationFailed) to(Disconnected)
608.361 Info UDPSocket.cpp:218: Closing socket
608.361 Info UDPSocket.cpp:248: Socket closed

fyi, you can ping me in discord (factorio server any channel) for faster communication.

That's very strange, there's nothing there that my mod would have caused, I don't think.

It's a mystery.