I am not sure why what you are doing won’t work but for some reason it appears like the wireless clients can’t talk to the Windows server to get IP addresses.
Did you restart the modem and server after you made the changes? Also maybe it is security on the Arris Modem to prevent a Rogue DHCP server?
It might help if the Arris WiFi will need to advertise the location of the DHCP server to the clients although the wireless side should just be an extension of the LAN.
I wonder if I wouldn’t put the Arris in Bridge Mode to a Router Model that is a bit more manageable with features like DHCP relay, etc… and also use a separate WiFi access point.
I also looks like Arris has a tech support number.
Hi, we have an AT&T Arris DSL Modem / wifi / router combo and I've disabled DHCP on it. The problem is that now clients who connect to the device's wifi do not get an IP address. Is there a way to setup Windows 2012's DHCP to accommodate wireless clients?