That's one (of many) reason I'm glad I switched to linux, Back in windows xp days Microsoft tried limiting the amount of "half-open connections" for its users "security". But even today, some routers just aren't powerful enough to handle too many connections, and often times the cheap routers that ISP's provide are limited on purpose either by custom firmware or just by hardware limitations.

How many torrents do you have??? I seed over 7000 torrents concurrently using qbittorrent