Check your firewall settings to see whether your bitcomet is in the exceptions list.If it isn't then make sure you put it in the exceptions list.But normally, the BC client would automatically have placed itself in the exceptions list.
If this does not solve your problem,check your NAT and DHT Settings and reconfigure it or you could change your BT client half open connections by going to tools-options then to TCP/IP LIMIT where you could change the default of 10 half open limit to either 50 or 100.You could as well download the half open software @ www.half open.com.(RECOMMENDED)