Hi Irek,
Thanks for the help. I am using an AT&T BGW210 router, which, if my googling is to be believed, cannot use UPnP, so I am trying to follow your instructions for port forwarding. This link (https://www.att.com/esupport/article.html#!/u-verse-high-speed-internet/KM1215101) gives instructions for port forwarding on this router, but I’m not sure what settings to use.
There is a “NAT/Gaming” tab in the router admin panel, with a drop-down list of applications, mostly the names of games. There is also a “Manage Custom Service” button on this panel, which leads to a screen with the following entry forms:
Service Name
Global Port Range
Base Host Port
Protocol (drop-down menu with TCP and UDP as the only options)
‘EnableUPnP’ is set to NX in server.cfg.