[Sorry for all the posts, but I think this is somewhat valuable for showing a method for debugging these sorts of problems and others may run into it soon as well]
I used 'netstat -a' on the laptop to look at all TCP and UDP ports, including those open for listening.
TCP port 6666 is open for listening. But UDP port 6666 is not.
So, my guess is that your Structure app comes up and does a UDP broadcast on port 6666 to announce that it's there, then the Skanect servers likely reply via UDP 6666 to allow Structure to build a list of client servers (and post the 'uplink' menu item).
Then the user clicks on 'uplink', selects a Skanect server, and it establishes a TCP 6666 connection to that server (which is then indicated on Skanect as showing that there is an 'uplink connection')
(at least that's likely how I would have engineered it- think it makes sense)
So, the problem seems to be that Skanect is not listening on UDP port 6666 on the laptop, hence it doesnt hear nor respond to the Structure client. So the question is- do I have the above correct? Should I see Skanect always listening on UDP 6666?