Ping Spikes when brother PC is connected

[edoroom]

Hi,
I'm pretty much lost and I really have no idea what to try more so I need your help!
Problem started about 2 weeks ago,Not sure how and what we changed that may have started it..
Our connection is like that..
2 PC (Mine and my brother) connected wired directly to the router. Just for knowledge router is also connected to NetGear Orbi which brodcast the wireless side of our network..
Alright so problem is pretty much easy,I mean its easy to see that the problem is coming from my brother PC as when its turned off ping is fine and when I ping 8.8.8.8 I'm getting constant ping of about 80-88ms which is what I should get,Gaming for example is totally fine,Other devices that are connected using the wireless like Xbox One,SmartTV working totally fine.When my brother is turning on his computer then spikes are starting,Gaming is impossible! only if he turns off his PC then I can play..
I did most of the basic things you might think,Antivirus scan,Checking each software that running on that PC,Running safemode with network only....Network monitor to see if there is maybe an software running in the background that taking all of the network..But after all even if I'm going to the network adapter and taking it from 1Gbps to 10mb then there are still spikes then in a bit lower like from 1800ms max to lets say 1200ms..
Next step I did to make sure its not a software or something so I disabled the network adapter and connected the PC to my android and opened an hotspot,Pinged 8.8.8.8 and was getting 120-140ms stable which is what I can expect for mobile internet..
So it means it's might be or the network adapter or the cable connecting from the router to the PC,However replacing that cable is pretty much a problem as its 26m cable that is going all over the house and I'm pretty sure the cable isnt the problem as how for example on speedtest the pc is still getting full speed 200mb download 5mb upload,Also I have made a test using the network adapter and it said the cable quality is excellent and I really hope its correct...
Updated driver of the network adapter to intel lastest and still same problem..
So my only guess is that the network adapter got corrupted but I really not sure on that..
If you have any suggests I will apperciate..
Also just did now a test with constant pinging 8.8.8.8 with my phone connected to the wifi and my PC (All when my brother PC is online) and the ping spikes happen in the same time..So what is wrong? :/

 

[Ralston18]

Check the IP address assigned to each system. Should be different IP addresses.

Take a look at your brother's PC and look for some application, process, or service grabbing bandwidth.

Could be some backup process, an update that is failing to connect, or his computer trying to connect to another network device: NAS or some share elsewhere on your network.

Run the Task Manager and Resource Monitor tools. First on your system and then again (with your computer off) on his.

Turn your system on, watch the tools. Then turn his computer on and watch the tools.

Good chance that something will show up via the Network tabs.

 

[edoroom]

Check the IP address assigned to each system. Should be different IP addresses.

Take a look at your brother's PC and look for some application, process, or service grabbing bandwidth.

Could be some backup process, an update that is failing to connect, or his computer trying to connect to another network device: NAS or some share elsewhere on your network.

Run the Task Manager and Resource Monitor tools. First on your system and then again (with your computer off) on his.

Turn your system on, watch the tools. Then turn his computer on and watch the tools.

Good chance that something will show up via the Network tabs.

Check the IP address assigned to each system. Should be different IP addresses.

Take a look at your brother's PC and look for some application, process, or service grabbing bandwidth.

Could be some backup process, an update that is failing to connect, or his computer trying to connect to another network device: NAS or some share elsewhere on your network.

Run the Task Manager and Resource Monitor tools. First on your system and then again (with your computer off) on his.

Turn your system on, watch the tools. Then turn his computer on and watch the tools.

Good chance that something will show up via the Network tabs.

Hi,Thanks for the answer.
As I said I already did it,
Also checked when only his computer is connected and problem is just on his computer but still cant figure out what causing it..

 

[Ralston18]

It that light, I would go back a step and try other Ethernet cables.

Just a single poorly terminated wire within one of the plugs on 26 meter cable could create such problems.

The long cable should not have any hard twists, bends, nothing sitting on it, no knots. If the cable has been secured in any manner, ensure that no nails or staples have pierced or pinched the cable.

Connects but not securely enough for consistent connectivity. Works, doesn't work, lags high and low; intermittent problems can be difficult to identify. So more work is needed to narrow things down and find the reason.

Inspect the 26 meter cable plug ends with a magnifying glass. Go online and find some images of properly terminated Ethernet cables so you will know what you are looking for. Compare to other plugs on other Ethernet cables that you have. You may be able to find some defect.

Longer cables tend to get tripped on, pulled, vacuumed up, stuff dumped on them, etc.. Not good at all.

Use a flashlight and inspect the Ethernet port on your brothers PC. Look for any debris inside and any signs of damage or distortion. Ethernet ports can be quite flimsy and a few plugs and unplugs (or cable jerks) can be destructive.