UDP Tracker no response

[The UnUsual Suspect]

bitcomet sends a connection attempt to each tracker, this has to pass through any firewalls and routers you have (there is a very good reason why we ask you to provide details about what you are using). If the tracker receives the connection they will reply and that connection has to make it through your router and firewall. You cannot assume that if one client works and the other doesn't that it's the client at fault, it could be that you have the same port used for both clients but only one can use the port, or the router settings could be correct for one client and not for the other.

Bitcomet requires an open internet connection to work and although we do attempt to help users setup their hardware to allow bitcomet, but in your case I don't even recall if you've posted a list of the hardware you are using or if you tried bypassing your router as I suggested... this would tell us where to look if it works without the router connected. Also I recall you saying is suddenly started working at one point... could that have been a time when uTorrent wasn't running? if you want two clients to work concurrently you need to have separate settings that don't conflict.