It could be, but you you haven't given us enough details on how things are connected, what subnets you're using, whether the Netgear is running as a router, or access point, etc.
im sure this is an easy fix.
That being said, I'd buy an Gigabit ethernet switch and plug all your computers into it. Plug it into your Arris router. Leave wifi disabled on the Arris.
Configure you Netgear router as an access point (do a google search) and disable it's DHCP server (get your DHCP from the Arris). Tape over it's WAN connection, so you don't accidentally use it. Run a cable from your new ethernet switch to a computer port on the Netgear.
With this in place, all your devices will be on the same network and you'll have GigE capability to the wired devices.