I am looking for an ADSL router that supports port redirection, and am looking at the 2820n. For example, I want to redirect all incoming internet traffic on port 8090 to port 80 on a LAN-side server. Is this possible with the 2820n?

Also, could anyone advise on how good the wireless range of the 2820n is? For example, does it carry a signal well through walls and windows? I'm looking for something that will provide wireless coverage across 2 floors of an office.

Yes, the 2820 series will do this port redirection, as well as several other variations on a theme. Specifically, the public port can be different from the private one. I have used this to take an external port 80 to an internal port 81 on the lan.

2nd, I have two 2820s in use. One gives excellent signal through a cavity wall the other gives average signal through 3 walls. That said I would consider the WiFi on the 2820 to be average as opposed to excellent overall, however all other features I would rate as excellent. VPN is particularly good.

If WiFi is really important to you then you may want to look at using a wired only router, 2820, plus an access point which you can place for best coverage wired to the lan on the router, e.g AP-700, AP-800, or shop around for another access point brand if that better suits your needs.

Don't get me wrong, the 2820n is a good router, but sometimes you need a non-integrated solution. Also, I don't trust WiFi in general because it's been mean to me