Flint 2: Terrible upload jitter/packet loss on FPS games unless I'm actively uploading a file or running a speed test?

Routers
1

I’m not actually sure if this’ll be a router issue yet. FPS games as of late have basically been unplayable for me due to upload jitter. I've tried everything I can think of. It took until today to realize something really weird:

My jitter graph goes 100% green when I'm on the upload portion of a speedtest, and the game is playable again. I decided to try uploading a large video (~21GB) to youtube, and sure enough - as long as I'm uploading something, I have no more upload jitter.

Any ideas what could be causing this? I have the power saving settings off on my ethernet adapter as far as I know. I need to get things working without having to be constantly uploading videos to youtube.

2

For me that doesn't look very surprised.

often the stability of a connection will lag if you upload when concurently downloading.

I noticed this myself when configurating sqm and decide to lower my upload to criminal low levels, I was able to higher the lat for downloading and still keep a A+ score.

But it can also be a issue by isp or equipment where upload becomes more than download.

is it wired or wireless?, try wired.

is a vpn involved?, try without it.

And there is MTU.

Often the max what most isp providers allow is 1500 mtu or maybe a bit more to allow vlans (1508).

The higher the mtu the faster the speed, but your network need to be able to support it, and the isp.

now the issue is, maybe something is putting you over this max mtu range, then this is likely why download becomes slower.

This is a pity in all gl firmware btw, the firmware doesn't respect the automatic calculations for mtu in OpenWrt, but lan already uses 1500 mtu, then comes ipv6, and you have 1540 mtu minimum and 1520 for ipv4, and then wireguard boom 60-80 on top of that, you may also use pppoe that also adds extra to the count.

^ i don't know the exact sizes, but this is one reason why to leave these mtu fields alone on the DSA configuration, it is very likely you are exceeding and this is how it looks like when the ISP is blocking this high mtu.

You could check what it shows when editing in advanced options -> network -> interfaces -> click devices tab -> edit br-lan, change mtu to empty and see with what it comes (backup before doing this).

My guess is to look into lowering the vpn mtu first.

3

That’s the weird thing, the issue ONLY occurs when I’m NOT uploading a
file. If I stop the youtube video upload my game will start lagging and having packet loss again. Download is never an issue, this is purely upload.

I am wired, no VPN, and I’m not too sure on MTU. I have SQM on with just the upload egress set to 30000. Turning off SQM makes no difference in the behavior.

4

Hmm that is indeed very odd.

I wonder do you experience also other symptoms like connection loss when uploading to high or downloading to high at max of your full lan connection?, and I don't mean normal loss but full network going down losing dhcp and layer2?

I'm suspecting you may use a mixture of STP,RSTP, MSTP versions, mixing them can cause these very strange issues, they can already be enabled on a network switch (if managed switches).

I experienced exactly the opposite of your issue.

On lan 1 i downloaded over lancache max speed, and the switch on lan2 started to sent packets with its own source address (mac from router), Flint 2 should have around 5gb/s switch capacity total.

And only when I used the max speed :slight_smile:

Can you check if that conflict is present?, it is known to cause really weird symptoms.

STP is designed to prevent loops, and it is good it is active, but mixing various types will cause alot of unstable network activity.

5

I think we want to do some comparison tests.

  1. Is there any other router to compare test? Or connect the gaming PC directly to the ISP Modem to see if the UL jitter is normal.
  2. How much jitter is measured by you through the online websites waveform.com/tools/bufferbloat, speedtest.net, and fast.com?
  3. Is there any other ISP modem to compare test, is UL jitter normal?
    Or, if there is a PC that you can build an OpenSpeedTest Server and connects to the MT6000 WAN with both static IP and same subnet?
    Topology like this:
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