Yeah, I have this because my ISP that's run by my flat has a firewall that limits the amount of connections.
On your modem/router or whatever, do you have a firewall? Check the config page (usually
http://192.168.0.1 or
http://192.168.1.1 ) and turn the firewall off. If you can't see anything or don't have a config, go to utorrents settings and on the connection page, limit the number of connections uTorrent can use at once.
The latter option may slow down your down/uploads though.