Flint 2 experiences severe connection instability when 1 specific PC is in use on LAN

So I just bought a Flint 2 today and set it all up. I didn't change too much beyond IP address assignment and set up wifi.

Everything works dandy, until my main bedroom PC starts doing ANY internet browsing. When I start loading or browsing any website all other PCs on the router start having constant dropped connections and packet loss, especially devices connected to the wifi.

If I unplug my PC from the switch/router (and just move it over to the modem directly) and leave the rest of the household continuing to use the Flint 2 they no longer experience any issues. Even if I go on my basement PC and browse all the same websites that were causing the issue, it doesn't happen so long as it's not my bedroom PC doing it.

I'm baffled as to why this is happening, my previous set up didn't have this issue, and like I said it goes away the second my PC is taken out of the equation.

Seems to me there is an issue with your PC. Could be a dozen different things that you'll have to troubleshoot and diagnose.

If it's specifically the PC then why does this issue not happen with either of my previous 2 routers? I even swapped back to my old, crappy RT-AX86U and there is no problems at all with the network, only when the Flint 2 is used

A bit strange.

If the PC connected the USB wireless card with the Flint 2, is it without issue?

I don't have a USB wireless card or any way to make the PC have a wireless connection as far as I know

Not idea, I also have Asus routers and never had this issue with Asus or Glinet routers. Start swapping lan cables. Update NIC ( lan and wifi ) divers on both PC's. Reinstall firmware on Flint 2 via UBoot.

Is the pc causing the issues using wireless too?

Then I have the suspicion what the cause could be.

Let me explain:

Wireless has more priority than wired that is because it is designed that way unfortunately.

So if a device is using alot of bandwith, it is expected to notice a little bufferbloat on wired clients.

But now comes the ugly part:

If a device is also far further away + taken all the overhead it needs to take to be wireless prioritized, it is even possible to make the full wired connections going down.

There are a few things which are concerning about this pc😉

  • why does it download that much?, if it is not by intend isn't it a infected botnet device?

How to fix such issue:

  • you can surely avoid this constant suspicious downloading/uploading, it is a red flag to me.
  • you can try to better the signal.
  • you can make it wired
  • sometimes from my own experiences, a main switch can also help creating more redundancy, for me this removed a few bufferbloat corner cases, but i don't think it solves this wifi issue.

Also what just cames up to mind, do you use usb connection to the flint 2?, that might also bigger the issue aswell.

I don't know why you're making this assumption about how much is being downloaded. I can see both on the Flint and my modem itself the PC isn't using any serious bandwidth, I can browse a few websites and cause the drop out issues while both the Flint and modem say I am using a few megabytes total at most during that time, just enough to actually load the websites themselves. It also has 0 traffic when I am not actively browsing.

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Indeed doesn't sound infected if you don't see it on the Flint 2.

Can you tell if the pc is on wifi and how far away it is?

Are we talking about a very isolated house too?

Is usb port involved on the Flint 2?

It's a wired connection, I don't use wifi on any of my PCs. The USB port is empty, never used it

Hmm, that is a very strange issue i'm afraid of not having a awnser either.

The modem you refer to in this quote:

That is not your Flint 2, but to your isp router correct?

if you ment your Flint 2 then something with this switch or router is not going as expected.

Do they use both the same dhcp range as dhcp server?

That might explain the issue for me, likely the Flint 2 blocks the connections.

if it is a switch maybe the switch is running on a bad implementation and sending the source mac address of the flint 2 and the flint 2 blocks the duplicates?, i got to say... I only saw this happening once on tp-link switches and with vlans, but neither i can't rule out the possibility of a bad switch.

Yes ISP modem. My setup is

ISP Modem -> Switch -> Flint -> PCs and other devices, wired or wifi

I have 2 gbit internet, so I use the Flints LAN1 2.5 port to connect to my 2.5Gbit switch so I don't bottleneck my connection. The switch is not the culprit, if I run any constant test to check for the drop outs, even as simple as ping -t google.com whenever my bedroom PC starts browsing I get a ton of Request Timed Out across all my network devices, but during that same time if I ping a local device through the switch without touching the flint (such as ping -t 10.0.0.105, my basement PC) I never get a single drop out. The drop out is happening on any connection passing through the Flint whenever my specific PC is using ANY bandwidth at all, even a few KB/s of throughout starts the issue across the network

My modem is on a different subnet, 192.168.0.1 is my modem, with the Flint I've tried others like 10.0.0.1 with DHCP between 10.0.0.100/10.0.0.255 as well as changing it to 172.16.0.1 as the Flint page says works and it also has the same issue

Yea it sounds not wrong, perhaps the range 10.0.0.1/24 could conflict with vpn, but you tried multiple so dhcp is not the issue.

There are no other routers or switches in front of the flint 2 or after towards the isp modem?

I edited my post above to add more context of the network setup, check it. Also to add on, I tried bypassing the switch and putting my PC directly into the Flint LAN 2, which now bottlenecks me down to 1gbps but the issue persists.

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I start to wonder if the issues relies on the 2.5gb ports itself, have you tried using op24 firmware perhaps?

Try flashing it without keeping the settings, i'm very eager to hear/learn if that fixes the issue since op24 has more recent support for 2.5gb ports.

i'm currently using Stable 4.7.0

Try this one:
https://dl.gl-inet.com/router/mt6000/open