Hello @Quincy01
The Meraki Go GX devices offer only a single WAN port. There's no bridge mode for GX devices from what I can tell. There is a cellular-setting on the GX-setup-page. But I guess this feature, even requested many times, never got activated or really implemented.
I do not know Xfinity, but some ISPs allow failover only if you run their modem/router in router-mode. IP-passtrough or DMZ aren't supported in that case, this would lead to a dual NAT situation, if you keep using a second router behind the ISPs modem/router.
I assume, your GX50 currently runs on DHCP-mode on the WAN port and gets the WAN-IP directly from Xfinity.
In order to use Xfinity failover solution, you would have to set the LAN on their router to a different ip-range then the one you use on the GX50. You might have to change the WAN settings on the GX50 to static and enter the settings manually. Gateway would be the ip of the Xfinity router, DNS can be set to a DNS of your choice.
There are some downpoints to this:
- If you run VPN or any other services on your network, you would have to set some port-forwarding rules on the ISPs modem/router all pointing at the GX50 and additional rules on the GX50 if they are on the GX50s VLAN
- The firewall of the GX50 kinda becomes obsolete, it only sees one ip on the WAN-port which is the one of the Xfinity device, it is still working but some features of it won't
- Your connection might slow down a bit because of the dual NAT
If you don't need a failover solution leave everything the way it is.
Hope this helps
Cheers