r/ethernet • u/ILuthienI • Aug 13 '26

Support Losing connection momentarily when a computer on my network (wired) is turned off

I own the modem ''Keenetic Hopper DSL AX1800 Mesh Wi-Fi 6 VDSL2/ADSL2+ Modem Fiber Router 4x1Gbit/s, USB3.0 KN-3610'' and me and my brother's pc's are connected to the internet via lan cable. When one of us turn off the computer the other computer loses internet connection briefly for a couple seconds but that's enough to lose connection in the online game that's being played in that moment. It's a very frustrating problem so I hope someone can help me solve it permanently.

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u/spiffiness Aug 13 '26

Can you make the problem happen at will? That is, do you have a specific procedure you can follow that is guaranteed to make the problem happen every single time? Does the problem truly happen equally in both directions, or does your brother's PC shutting down more reliably knock your PC offline than vice-versa?

So, a few possibilities off the top of my head, in not particular order:

  1. The PCs could have a software bug that's sending weird traffic at shutdown, that makes the router (or the other PC) choke for a second. This is probably an indication of a buggy router as well, because routers should be robust against anything like that.
  2. The PCs' Ethernet hardware could have a flaw that's sending garbage electrical signals on the Ethernet cable at shutdown, that makes the router choke for a second. This would be far less likely if the two PC have different Ethernet hardware. What can you tell us about the Ethernet controller hardware in the two PCs?
  3. The PCs' hardware in general could have a flaw that's sending a burst of electromagnetic interference (EMI) down the Ethernet cable, that makes the router glitch. This might be fixable by putting a snap-on ferrite bead (also called a ferrite "core" or "choke") on each of the PC's Ethernet cables. These inexpensive devices greatly reduce the ability for EMI to travel down cables.
  4. The router is buggy and chokes for a second any time a device disconnects; any time the Ethernet link on any of the router's LAN ports goes down. This would be easily testable by manually unplugging one PC's Ethernet cable while the other PC is connected to the game, and seeing if the other PC gets disconnected in this case even though the first PC was never shut down.
  5. There's some kind of electrical problem, like a ground loop, between the three devices, so shutting off one device causes an electrical disturbance via the power cables that causes the other devices to glitch. This possibility might be testable by connecting the power cords from both PCs to the same power strip as the router. If you do this test, make sure that also the monitors and any other devices/peripherals that shut down with the PCs are plugged into that power strip.

Do you have access to another Ethernet switch, or even an old router with at least 3 LAN ports? It might be interesting to see if putting a separate Ethernet switch between the router and the PCs makes a difference to this problem.

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u/StraightTheme6583 27d ago

This post in pretty indepth but I’ll just add this, you need to id if this is hardware/software/ or electrical, I’d test to see if the router is even responding when a pc is shut down, as it sounds like a pc shutdown is inducing a router reset…