I owned more than one G1100 so I tried to set one up downstream of an SB6183 Docsis 3 cable modem. It has a lot of good features including 802.11ac. However, a device called the OBI 200, which worked flawlessly when the G1100 was connected to FIOS via the WAN port - lost all ability to communicate with the internet once the SB6183 was providing the broadband to the G1100.
I can't imagine this is a firewall issue or it should have filtered the OBI packets regardless of what was happening on the WAN port. Do I have one too many DHCP servers coming into play? I thought the G1100 was smart enough to get an Optimum IP address through the cable modem and still provide DHCP to all of the connected devices. Most devices I connect are working fine - both cable connected and via WiFi - all getting IP via DHCP from the G1100. I connected the OBI directly to the cable modem to make sure neither the SB6183 nor the cable company were blocking the traffic.
After some research and much trial and error - following instructions to disable DHCP within the OBI 200 and assigning a specific IP address resolved the problem without having to shut off firewall or do DMZ server. I have no idea why the extra hop caused the default setup to fail - perhaps multiple DHCP services accessible in the environment? The ARRIS surfboard is not supposed to have DHCP services as it is just a "plain" modem but I am no DOCSIS expert so I can only speculate. Thanks for letting me request some feedback and assistance.
This unless mistaken has nothing to deal with FIOS other than you are using/were using a FIOS router, but I will give to you my two cents.
#1 The max number of CPEs.
As noted in my screen shot, I have a max of 2 and I am using one of them.
#2 Yes there is a DHCP Server in the cable modem even while it is not a modem with a built in router..
As noted in this other screen shot of mine, it says
The SURFboard cable modem can be used as a gateway to the Internet by a maximum of 32 users on a Local Area Network (LAN). When the Cable Modem is disconnected from the Internet, users on the LAN can be dynamically assigned IP Addresses by the Cable Modem DHCP Server. These addresses are assigned from an address pool which begins with 192.168.100.11 and ends with 192.168.100.42.
This cable modem of mine does not inlcude a NAT router. From the help page, it tells the model number.