Computer affecting broadband on other devices

My main computer running Windows 8.1 started showing low and erratic broadband speeds a couple of weeks ago. The same effect was seen on other devices so assumed it was an ISP problem. After contacting them and doing the usual tests including using a different router the problem remained. I tried to investigate further and discovered when the main computer was switched off,. other devices worked normally with the usual ADSL2 speeds(12.5). I assumed it might be the network card on the computer and tried a wireless dongle which had the same problem. TBB speed tests show a very high latency often over 400 ms.

The TBBx1 speedtest seems most affected with speeds varying between 1.26 and 7.43, the Burst test usually gives a higher figure up tp about 9 The TBBHttpX6 usually gives higher speeds eg. 11.8 and Burst 13.5.. Upload speeds seem to vary between 0.1 to 0.2.

Any ideas what maybe causing the problem on my main computer which affects all the devices on my network? When the main computer is on broadband speed on all the devices become very erratic.

I have tried the usual things including deep testing for malware etc with nothing found.

First thought would be virus/malware on that system, or maybe some program eating resources that it shouldnt be. Might be worth using the tbb bandwith meter on these forums to monitor usage on the PC

I remember last year when i turned my Xbox One on it would slow my connection down. Turned out the xbox for some unknown reason was uploading a large amount of data. Factory reset of the machine fixed it.

Edited by bobble_bob (Wed 15-Jul-15 13:45:25)

Could be a hardware failure with the network card causing broadcast storms or could even be a dodgy cable causing large amounts of retransmits.

Yep, had that problem with second desktop, until I connected it by WiFi....
Martin

Have you got a P2P seed running on it, supplying people wanting the feed? If your upstream is saturated the downstream will die.

Edited by RobertoS (Fri 17-Jul-15 00:44:21)

Thanks guys for the replies. I have not discovered any P2P programs and changed the cables. On thing I get on the TBB test is a comment that RWIN may need changing. I was under the impression that Widows 8.1 had sorted that out and not sure if that is possible or likely.
Alan