Mark Rogers wrote:
Well a typical download requires you to "upload" the request (eg for web browsing lots of separate HTTP requests), and also TCP will require a fair bit of handshaking (ie sending messages back), so when you run out of upstream bandwidth everything grinds to a halt. But according to the bittorrent software I'm not getting anywhere close to the limits, and it is often the case that another PC on the same LAN can access the internet fine even though I can't from my desktop, unless I kill the torrent software.
Out of interest, How do PC to PC transfers within your Lan perform when the network is in this state. So from your torrent machine to another box on your local subnet ?
Also is the PC with the torrents running on wlan or an ethernet connection ?. If it is on wlan do you have other machines on a wired connection to your router and are they unaffected when the rest of the network is in go-slow mode.
Finally you could use something like mtr, http://www.bitwizard.nl/mtr/ to trace to an external ip and give you a running average of the hops to your router and beyond and see if and where the latency increases when the network is in this state.
Answering those should at least allow you to eliminate your internal lan or the torrent machine itself, some cheap consumer grade routers do struggle with a high number of connections. But with something like mtr it should be possible to watch the hop across your local lan to the netgear, the hop from that to the virgin router and then the hop from the virgin router to its gateway and then possibly spot where the problem is.