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.

The WireShare 5.6.4.1 (Java 1.6.0_65) on the iMac (OS X 10.9.4 Mavericks) with the default installation takes one minute to connect (turbo-charged with five green first to eventually blue bars).

It is set as 32-bit mode in the
Finder - Get Info
and has the
WireShare - Preferences - Advanced - Listening Ports
as
Gnutella port: 6346
Use Universal Plug 'n' Play (Recommended) SELECTED
Manual port forward: 6346 NOT selected
BitTorrents ports: 6881 to 6889
Use Universal Plug 'n' Play (Recommented) SELECTED

On the other hand, the
Tools - Advanced Tools
shows
Port 6346
and shows five connected servers eventually.

With the same configuration, WireShare on the Mac mini never connects (shows Connecting all the time with all the five bars gray) and takes a frustrating 20 minutes to check all servers at
Tools - Advanced Tools
and shows
Port 6346
on such window with no connected servers at all.

During such 20 minutes, up to three "WireShare has encountered a problem" pesky windows show (stacked one below the other). If you close them all manually, they show again for such 20 minutes. During that period you cannot select any menu or change any configuration until you close all and every of such pesky windows, and since they show again after two or three seconds once manually closed, it is almost IMPOSSIBLE to do anything during such 20 minutes (not even quitting WireShare, until you close such pesky windows, which is not easy since they reproduce after two to three seconds). REALLY FRUSTRATING. I think that such window is shown every time that
Tools - Advanced Tools
scans a new server with no connection, since after 20 minutes such scan stops and also the pesky window do not show again if manually closed. Update: it shows again (up to three stacked windows as well), but if you close them manually they do not show for 1 minute and 30 seconds (instead of two or three seconds as described above), so is less frustrating.

It would be great if such pesky window showed ONLY ONCE in future versions of WireShare, or at least did not block selecting menus, changing configurations, etc as now happens. As said this is the most frustrating part, besides not having connection, of course.

But there is something else which is weird. Even if I set the
Manual port forward: 6346
on the Mac mini, and later on I select
Use Universal Plug 'n' Play (Recommended)
when I close such window and open again or when I quit and open again WireShare, it has changed to
Manual port forward: 46189
even though it is not selected, because the
Use Universal Plug 'n' Play (Recommended)
is selected as said. So, it changes automatically from 6346 to 46189. I do not know if that gives some clue of what is going on, or if it is relevant at all, but that does not happen on the iMac where ShareWire works. Doing more testing it changed from 6346 to 50672 on both
Gnutella port
and
Manual port forward
even though the
Use Universal Plug 'n' Play (Recommended)
was selected. But remained as 6346 on
Tools - Advanced Tools
Just in case such information is useful.

As always, any idea will be most appreciated.