At my wits' end with packet loss (maybe QoS issue?)

DKskelr · February 17

Hey guys,

I got a weird problem with packet loss in my new apartment (location = Germany).

Setup: Router (Fritzbox 7530AX) as modem

LAN 1 = Gaming PC
LAN 2 = Router 1 (2nd floor)
LAN 3 = Router (1st floor)

Line = 100MBit/s down, 40MBit/s up (VDSL/Vectoring)

I am experiencing heavy packet loss on my gaming PC (MB = Dark Hero VIII) in various games (Valorant, Overwatch 2, CS2) whenever another device (whether it is a TV connected to LAN 4 or a simple phone via wifi) uses even a bit of bandwith.

What I did:

replaced the modem with a Fritbox 7590, another 7530AX, a 7590AX --> same issue
factory resetted every device -> same issue
replaced every cable -> same issue
asked my ISP to check my connection -> they found nothing
tried different firmware versions for my modem and played around with its rather limited QoS settings -> same issue
tried different circuits and even a different PSU + motherboard to make sure that it isn't due to some interference within my apartment -> same issue
switched every other fuse off -> same issue
disconnected everything from the modem except for the gaming pc (wifi was off) -> no packet loss

So the packet loss only occures when at least one other device (no matter whether it is a smart lightbulb, an apple tv, a smartphone or another pc) uses even 1% of the total bandwith (monitored via my modem's gui). I am aware of bufferbloat and had a setup at our old place where OpenWRT was running. I decided to switch to fritzbox products (very common in Germany) in order to be able to easily cover the whole apartment with a decent enough wifi signal.

Is there anything else I could try to solve this issue?

SpookyCitrus · February 17

100MB download 40MB upload is pretty meh, could be a bandwidth issue. Do you have your gaming computer plugged directly into the modem or the router? If it's plugged into the modem directly, try it plugged into the router instead. Also see if it has packet loss using WiFi instead of being hardwired.

DKskelr · February 17

26 minutes ago, SpookyCitrus said:

100MB download 40MB upload is pretty meh, could be a bandwidth issue. Do you have your gaming computer plugged directly into the modem or the router? If it's plugged into the modem directly, try it plugged into the router instead. Also see if it has packet loss using WiFi instead of being hardwired.

You are right – it is not great but still above the average speed for an internet connection in Germany (see e.g. https://www.statista.com/statistics/1338657/average-internet-speed-germany/). Infrastructure just sucks in Germany and fiber is still unavailable in many areas… Besides, even while gaming, I am using 15mbit/s down and 3mbit/s up at most (in total).

In terms of setup (modem>router>pc vs. modem>pc) I tried both, even tried different devices, another pc, used pingplotter on different PCs/Macs, all connected either via wifi or lan. The result is always the same: Whenever another device uses even a fraction of bandwith – even a traceroute is enough –, packet loss starts on any other pc within the network. When this happens, I am using not more as the bandwith stated above (15/3).

SpookyCitrus · February 19

On 2/16/2024 at 5:41 PM, DKskelr said:

In terms of setup (modem>router>pc vs. modem>pc) I tried both, even tried different devices, another pc, used pingplotter on different PCs/Macs, all connected either via wifi or lan. The result is always the same: Whenever another device uses even a fraction of bandwith – even a traceroute is enough –, packet loss starts on any other pc within the network. When this happens, I am using not more as the bandwith stated above (15/3).

This would most likely be an ISP issue, I'd recommend calling your ISP to see if they can run remote diagnostic on your service. That or the router itself is bad? I see in your OP that you have tried different modems and cables, but it doesn't say anything about a new router? Unless your modem is a combo modem/router unit? I'd say really all you have left to test is a new router, if you haven't' already. If that doesn't solve the issue it's a problem with the service and you'll need to contact your ISP.