LOTR (and Dubbin)
Your posting on UPnP not being totally reliable is true and manufacturers seem to implement it in a somewhat hap hazard manner. However, I did not want to add to Dubbin's confusion by revealing this bit of information without him trying it out first.
Remember, if it works on his set up then his problems are solved, if it doesn't work then his only course of action is port forwarding.
You know, I still remember from five or so years ago when I had to port forward my first modem router, I went grey and then bald from the experience
, until
Wondering Why came to my rescue.
So rather than put Dubbin through the same pain, I would suggest and encourage him to try UPnP first before anything else.
UK Bob