Hi all
Dunno if this helps anyone... but I thought I'd share it just in case.
I couldn't figure out how to host a game successfully - I'd set up port forwarding and opened up the port in my firewall, but it still didn't work.
The solution ended up being, setting an option in my router (Netgear MR814) such that it responds to a ping from the internet (the router default was no). Hey presto, all works now :)
Belmakor