Some routers will allow you to install thirde party firmware. Such firmware (effectively the operating system of the router) can have more tweaks than the standard settings so you can get a workaround.
The real problem is the way torrents work. The software is continually sending out connection requests, and receiving them from other computers. This applies even to the computers you are not uploading / downloading, as the torrent software is always searching for a better connection. Trouble is the connections usually stay open for a while after they aren't needed. In turn this uses up the router's memory tables, until something crashes. I had that problem on my Linksys WRT54GS, until I did a
found the DD-WRT firmware and the settings to go with it.
A short term fix is to limit the number of concurrent connections in your torrent software. Most people won't need many more the 60-100.
I'd advise against your fixed IP setting for the router to modem connection. One unexpected reboot and all sorts of unexpected stuff could happen. Plus there may be clashes on the VM network if the network lease on your IP expires.