SG-3100 installation behind Comcast Gateway Modem

[CootieBadger]

Hello -

I'm helping a friend install a new SG-3100. He currently has a comcast business modem that cannot be put into a true bridge mode. The workaround I'm trying to do is put the SG-3100 in the DMZ. Turn off DHCP on the Comcast modem, and then have his network switch run from the SG-3100.

Details:

Comcast modem = 10.1.10.1 - DHCP disabled

SG-3100 = 10.1.10.2 in the DMZ - Set to dish out DHCP 10.1.10.0/24 connected to Comcast modem via Lan1
WAN set to DHCP, DNS 8.8.8.8, .4.4

Network switch connected to Lan 2 on the SG-3100

The setup was working for 2 hours or so. LAN traffic was fine. File shares accessible, internet accessible. I ran the software update that the SG-3100 wanted 2.4.x. The update installed, the SG-3100 rebooted, got a solid orange light on the SG, no internet. Rebooted the SG again, light went away. LAN traffic is fine, no internet.

Any ideas if this was the update or does something seem out of whack with my setup?

Any help is appreciated.

Thank you!