Constant LAN disconnects

I just got back from holiday so the pc hasn't been used for a a week but since then my internet connection has been intermittent in the extreme, this is not an exaggeration, it cuts out for 12-13 seconds a time on average I guess about once every 3 minutes, though it can go 10 minutes occasionally without a disconnect. This only affects my PC as its the only device wired for the internet, wifi devices do not seem affected.

I have had this problem before but my previous solution has not fixed it this time. Previously I thought it was my ethernet cable so I replaced it, no change. Then I thought the issue was with router or ISP (Virgin Media/Superhub 3), so I ran the diagnostic tool which said:

"the device connected was running at a lower speed of 100mbps and is not utilizing the full available speed"

I spoke to my ISP but after I contacted them they told me that it seemed like my network card could be throttling my connection as it couldn't be the cable because that was new. I checked int he network settings and noticed that the Speed and Duplex was set to 100mbs, I switched it to auto negotiation and the problem went away.

I have checked that this time, it was still on auto negotiation so I switched it to 1.0 Gbps full duplex to see if that helps, no change though.

I don't know why, but if I am downloading anything, for example, a game on steam, the connection is fine and stable for the duration of the download.

I just want to add that I have already asked this on another forum and they are as stumped as I am, feel free to have a look at what has been suggested there but the gist is:

All drivers are up to date.
WiFi is not affected.
No Virus or Malware found.
BIOS is up to date.

Thanks in advance for any thoughts or ideas.

I would check cables. Replace with known good ones, even temporarily, as a diagnostic tool.

What cable are you using is cat 5 cat 6 this will effect speed set as full duplex will often kill it as it sends and receives at the same time and often PC or router can't cope if it's not getting gig settings by auto it's because something is wrong

samuria said:

What cable are you using is cat 5 cat 6 this will effect speed set as full duplex will often kill it as it sends and receives at the same time and often PC or router can't cope if it's not getting gig settings by auto it's because something is wrong

I am using this CAT 6 cable. If the cable is the issue and it is faulty though, wouldn't the disconnects persist even when I download something? Why would the connection become more stable when it has a heavier load?

I don't have another cable that I know is good so I will get hold of one tomorrow and try that.

If your router shows 1000Mb light on the ok for cat 5e or cat6. I would replace cable (borrow from a friend?) or buy new one or a tester....

chitownbob said:

If your router shows 1000Mb light on the ok for cat 5e or cat6. I would replace cable (borrow from a friend?) or buy new one or a tester....

It was the cable. Didn't think it would be but it was, at least the connection is stable now. What could cause a cable to go bad like this? It was only 6 months old.

Hardware is more likely to fail than software, since a huge pool of users get the same software. People forget that cables go bad.
Why? I make my own cables (not a pro) but see them go bad on occasion. Once was my cat chewing on them. Personally, I suspect that it is hard to quality control them. You have eight tiny wires connecting to the rj-45 jack. When you made them, they tested fine. Lets say one is a tiny bit longer than the others... So more strain. Eventually it breaks and no or poor connection. A boot helps but taking it easy on cables when moving computer does too.

LaserChild9 said:

What could cause a cable to go bad like this?

An imperfect clamp job can come loose with the slightest tug