I've never had a problem with my TGN797v3 working with my Wifi Printers, I have a Canon Color printer, and a Samsung Laser Printer. Of course the TGN799MAX might be (ahem) not as good.
Do other devices connect to the Gateway via it's WiFi?
If other WiFi devices connect, then yes, it would be. If not, then connect either a laptop or a PC to the gateway via Ethernet and check that the WiFi setting are correct, and the Wifi is ticked ON.