Does that router have a firmware upgrade available for it?

No, there's no firmware update yet.
The website makes mention of a pending firmware however. This firmware upgrade should enable 54Mbps performance with the existing 22Mbps USR networking products.

There's no mention that this firmware upgrade will fix anything else than this 54Mbps upgrade, but I guess that it's possible.
The upgrade is already available for all the other USR 22Mbps products, but no yet for the router. So I expect it any day now.