Help, total non-technical person here. I thought slingbox was supposed to be plug and play?

I have called the help line 3 times now. Each time the slingbox starts working, then a couple of days later I go to use it and it can't find the port forwarding.

I go into the netgear setup and can see it there but nothing.

Please help - in basic english

I have a macbook, netgear router and Virgin+ box