[2.0.32] Multiplayer FPS Drops/UPS Spikes

[ezekiel]

I am playing multiplayer with my friends. The server is on my LAN so I connect directly, and my friends connect to it over the public internet.

I experience intermittent (every few minutes, or more) dropped frames and UPS spikes. The UPS will often rise well above 100 UPS (presumably to catch up to the server) and the frame-rate will completely stall out for a second or two. None of my friends say they experience this issue, and given how noticeable I am inclined to believe that.

I've done some research already and I understand that this happens when my client computer is unable to keep up with the hosting computer and then has to drop frames to keep up. I am running this on an M4 MacBook Pro with 24GB of RAM. The hosting device is an M4 Mac mini with 16GB of RAM - so the devices should be very close in performance. Both have active cooling, same CPU, GPU, etc.

1. My first step is setting my graphics settings as low as possible (see image). This does not resolve the issue.
2. My next step is loading the server with `game.speed = 20` to stress the machines. My idea here is to eliminate performance gaps between the devices. With this setting, I see a FPS/UPS of 200/1200 confirming that my client machine is capable of handling the high update rate on this same map. (see image).

Also attached is a screenshot of the render update step when the issue occurs.

At this point, I'm at a loss. If my computer is capable of doing FPS/UPS 200/1200 then why is it dropping frames so poorly consistently only when in multiplayer? If I can attach anything specific for people to look at please let me know.

[eugenekay]

What is your Network Connection between the problematic Client and the Server - are they on the same Ethernet LAN, or is the client connecting via WiFi? What is the Ping time of the Remote clients?

I have seen this happen on my Local Network with a WiFi connection; it seems to especially happen during times of High Interference (eg, Microwave Oven active nearby) that causes a drop in Signal Rate or even a downgrade from 5Ghz to 2.4Ghz…. Because Factorio is UDP based any missed packets may not immediately be noticed until the Game re-sends them to prevent a Desync. Because your Client is “local” it will have a lower Ping time (and thus, Tick-lag) to the Server - until some Packet Loss occurs and the Client must suddenly “Catch up” with the server’s changes, lest it fall behind. With remote clients they are already operating a few Ticks behind (the game does a great job of hiding input Lag so you don’t notice this since 1.0), so if a packet Drop occurs it may already be re-sent before any Lag becomes obvious.

I reduced this problem by moving my Microwave away from the Access Point.


Good Luck!

[ezekiel]

It being a network problem would explain the intermittent nature of the issue. The server is connected via ethernet to the router, and the client is connected via 5Ghz Wi-Fi to the router. Usually the game reports <10 ticks of latency and single-digit buffer values, but those sometimes jump higher.

I'll do some network analysis to see if I can reduce this. Thanks for that insight.

[ezekiel]

Because your Client is “local” it will have a lower Ping time (and thus, Tick-lag) to the Server - until some Packet Loss occurs and the Client must suddenly “Catch up” with the server’s changes, lest it fall behind.

I'm definitely staying on 5Ghz, but I've been trying on the ethernet cable and tentatively that is fixing the issue. I'll remark back here if I find that's not the case but for now I'm satisfied that there's interference on my Wi-Fi signal.