Yeah, upgrade to Gen 5 and it's the printers fault.
Try this. Hard reset the new router back to Factory Defaults. Once done reconfigure the router back to your own settings.
Now use the printers Wireless Setup Wizard to connect your printer to your routers SSID and password. Are you successful?
If not, remove and disable all security off the router temporarily. Now try to connect the printer to the routers unsecured SSID with no password. Are you successful?
If yes go back and add WPA2-AES on the router with a valid password and try again.