Thanks again for all the replies.

No problem with FrostWire 5.7.5. It connects turbo-charged in one second.

It is clear to me that this is something LimeWire-related and as said, I am experiencing this problem since many months or even years ago, when I updated its version at some point. And since WireShare is LimeWire-based, the issue remains. But I wonder what is it.

No problem with my ISP. It has no restrictions at all for sure. My email for gnutella forums is not related to my ISP. I think the problem there is related with hotmail.com blocking somehow emails from gnutella. I have no filters to block hotmail at all.

Little Snitch is the best firewall for Mac, but initially you have to let it know the accept/reject connections, which may be a bit tedious. Once done (a few minutes during the first days after installation), it runs in the background like a charm. Little Snitch has nothing to do with my email. I am not using a blocklist with Little Snitch. I will try later on to disable Little Snitch, but I guess that is not the problem, since the iMac in which WireShare works has the same configuration and works as said.

Mavericks Gatekeeper is disabled.

So, here we are.