Networking – Torrenting crashes internet connection

I'd suggest going to Control Panel --> System & Security --> Administrative Tools --> Event Viewer, and looking in the Windows Logs, I believe the System and also Application logs will give you a better idea of what may be crashing the system. Look for the Red Exclamation point under the Level category called Error.

(Shouldn't the kernel be divide time among processes that request to send/receive packages?)

The typical situation with having slow or no Internet with something like Bittorrent saturating your connection is that incoming traffic on your upstream (which is usually lower than your downstream on most residential connections) is crowded out. So incoming TCP ACKs are not received timely, and connections timeout on their end, and then eventually your end.

One thing I learned from studying QoS is that there is no such thing as QoS on incoming traffic, because you can't control what's being sent to you. You can only really QoS/divide/share outgoing traffic. You can see the current Linux QoS configuration with tc - but be warned, tc is very complicated.

It's possible that a single connection could saturate your incoming bandwidth and crowd out incoming TCP ACKs, causing slowdowns, drops, etc. The number of concurrent connections doesn't really matter.

You probably need to set the total amount of bandwidth your Bittorrent program uploads to just under your maximum upstream, like 8Kbit/sec below what you know is the speed of your upstream. You also might want to look into Wondershaper if you feel like going down the rabbit hole that is QoS on Linux.