Thanks for all the support. I have installed the latest FrostWire 4 (4.21.8) for Mac, yet it does not open in OS X 10.9.4.

I have turned off both the Mac firewall and Little Snitch, yet the issues remain: LimeWire does not connect and WireShare does not connect and shows the pesky window ("WireShare has encountered an internal error").

I have deleted all rules for LimeWire on both firewalls, and when opening gain LimeWire, both firewalls ask for permission. Yet, there are no rules for WireShare on either firewall and they do not ask for permission ever about WireShare. Anyway, I have added WireShare to both firewalls granting permission to no avail. The issues remain.

Yes, I port forwarded the router, using such ports for LimeWire and WireShare to no avail. The issues remain, even using Universal Plug 'n' play (recommended).

The other Mac (iMac) works OK with WireShare as said, which means turbocharged (five blue bars) in a second. Both Macs are connected to the same router. I have FTTH (200 Mbps symmetrical connection).

Disabling all Ultrapeer, DHT and TLS does not fix the issues on LimeWire or WireShare.

Amazing. I wonder what is going on preventing LimeWire and WireShare connecting on the Mac mini.