Very slow to No internet connection

Wasn't sure exactly where this belonged, but figured I would put it here as it seemed more of a networking issue (although it may be a Linux issue)...

Over the last couple of weeks, I have had intermittent issues where the internet starts lagging down substantially. Normal ping responses are roughly 50 - 60ms. But times get up above 1500ms and will often say time out.

Been talking to my ISP regarding this, and have been trying to consider things that it could be on my end. Initially, tried a different router as the one I've been using is over 5 years... Brand new router had same issue. Tried new cables... Same issue... Eventually I figured out that if one of the network cables in particular is unplugged from the router, it works perfect...

So the issue:
The cable that needs to be unplugged for it to work is my server (Fedora machine which is probably well over 10 years old). If I turn the server off and then back on, it works fine. But then after several hours, it stops working properly.

So my question, what can I check or look into on my Linux machine to see what the issue may be. Why it stops working properly, or starts lagging the network?

Thanks for any advice you guys may have. Please move the thread if needed. If you need further info, let me know.

Some cli root utilities I use in fedora are iptraf, ntop, htop, traceroute, wireshark. I'd probably start with traceroute and/or wireshark run on the offending fedora machine to see if there is any unusual network traffic.

Also from your description look for any memory leaks in the fedora box. And if your fedora version is not up-to-date (fedora 16 currently) you should think about updating to the current version. Older repos are not available for getting any program updates via yum, you will need to fish around on the internet to find any update rpm's.

I agree with Doug. Check for a memory leak when it's occuring. Also, fire up wireshark and see if the NIC on your Fedora box is flooding the network; possibly a faulty NIC if it is.

Your best start to see where the issue is traceroute. If it's on your side you'll know it quickly.