Try typing 192.168.0.1 into your browser, see if that gets you into your router. By default the username is admin & the password is password. Click OK to log into your router.
If enabling UPnP doesn't work for you & you want to try port forwarding, you'll find the instructions here. Don't forget to set up a static IP address first!
http://www.portforward.com/english/r...DG814index.htm
There are 2 DG814 routers, one a straight 814 & one an 814v4.0... the link above is for the 814.