One computer in my network has an extremely slow connection to the Internet.

[Kokoloko]

Hey,

since 2 days ago, one computer in my network has an extremely slow and "stuttery" internet connection. I didn't install anything for 2 weeks, and neither Malwarebytes nor Norton found any Malware on my Computer. However, 2 days ago, a windows update was installed (KB2975719, it failed one time and succeeded the 2nd time) and yesterday another one was installed (KB2989647).

My network looks like this: 3 computers, 1 of them connected directly via LAN to the router (with integrated cable modem), which gets the full 32 mbit/s down and 6 mb/s up. 1 laptop connected via Powerline (Fritz Powerline 500E to Fritz Powerline 520E), which has 10 mbit/s down and 5 mbit/s up (it's a fairly old laptop and I don't do much that requires fast internet on it, so I never looked up how fast it was before). And now the problematic computer: Also connected via Powerline (Fritz Powerline 520E to Fritz Powerline 520E), which only got ~100-200 kbit/s down and 20-50 kbit/s up for the last 2 days. Previously it also got 32mbit/s down and 6mbit/s up for several weeks without any problems. All of these values were taken without any other program or computer using the network at the same time.
Additionally, the connection seems to "stutter" only on this computer: Here are 2 examples: https://i.imgur.com/3GEIU3o.png (10 seconds in a speed test) and https://i.imgur.com/ItPh4b7.png (60 seconds of trying to max out the connection, aka downloading a file from a high speed server and doing some browsing simultaneously).



System specs (if you need additional information, please ask, I will only list the most relevant parts):
Asus H97-Pro (Intel I218-V Nic)
i5 4590
8GB G.Skill DDR3 1600
MSI R9 280
Samsung 840 Evo, Crucial MX100, Seagate 1TB
Windows 8.1 64-Bit.

What I already tried: Resetting and restarting the router, reinstalling the driver for my NIC and also trying to use an old driver for my NIC, resetting all powerline adapters, checking cable connections and using different sockets, flushing the DNS cache (ipconfig /flushdns, ipconfig /registerdns, ipconfig /release, ipconfig /renew, netsh winsock reset), turning off power saving options and manually setting the speed to 1 gbit/s full duplex.

Sorry if I made any mistakes, English is not my native language. If you need additional information, feel free to ask.

I hope someone can help me!

 

[getochkn]

Have you tried plugging the computer into where one of the other ones are that get good speed to eliminate the powerline adapter. it could just be going flakey, a new fan could be plugged in anywhere in the house and add distortion to the line. First thing I would have done would have been move the tower and try it directly on the modem itself, or the closest router than another computers good on. Powerlines are flakey and something plugged in somewhere else in the house can decimate their speeds.

 

[viewtyjoe]

Have you tried plugging the computer into where one of the other ones are that get good speed to eliminate the powerline adapter. it could just be going flakey, a new fan could be plugged in anywhere in the house and add distortion to the line. First thing I would have done would have been move the tower and try it directly on the modem itself, or the closest router than another computers good on. Powerlines are flakey and something plugged in somewhere else in the house can decimate their speeds.

This. You need to establish whether the issue is cable/powerline related or NIC related. From there you can determine the next best step.

 

[Kokoloko]

Ok so I just switched the powerline adapters and now I'm getting at least 15 mbit/s again. It's still only half of the value I had before, but it seems it is a problem with my adapter, so I will buy new ones. Do you think that I might get the full 32 mbit/s with new ones again? I think it's really weird that it seems to be a problem with my adapter, yet I don't get the full speed with a "working" one either. I can remember that I still got 32mbit/s a few days ago and I have changed absolutely nothing in regards to what needs power in my house.