My AT&T Fiber comes with a DEMOX router that also includes Wi-Fi. However, I do not want the AT&T Router to do anything besides translate light into electrons and feed my ICX7150. I want the ICX7150 to perform DHCP assignment and DNS assignment. I do not want to be forced to AT&T DNS (they prevent you from changing the DNS to reduce tech support calls).
Initially the ICX7150 was set up by the previous owner, and it was running very old firmware, I think from 2017. So I upgraded the firmware, but I forgot to note which firmware was on the switch (was it S or R I don't' know). I have loaded S (switch) but now I lost my AT&T internet. I have also reset the AT&T router to the defaults since I wanted to start from scratch.
The Wi-Fi and internet provided by the AT&T router works fine, it's the ICX directed Wi-Fi that is no longer routing and neither is the ICX.
I have set the ICX to static IP and that IP, and Gateway are on the same IP network and subnet as the AT&T router, mainly the 192.168.1.x range.
The gateway of ICX is pointing to the AT&T Gateway IP.
So should I switch ICX to routing, and what exactly do we lose between ICX acting as a switch vs a router?
When your ICX is running switching mode, it's just a plug-and-play hub. By default, all the ports will belong to the same VLAN and no other functions will be performed, other than just switching the traffic between the users and your provider's router.
If you would like the ICX to run as Router, that will require a deeper understanding of the configuration of your provider's router, as the DHCP, DNS, NAT, and Routing functions are programmed by default in the provider's router, this needs to be disabled before you enable it in the ICX.
The ICX in router mode will need a default route to be configured so you can tell the device where to send all the traffic that goes out to the Internet. But it doesn't come with NAT capabilities, so the provider will still need to do the job. Basically, you would need to point all the traffic towards the provider's router as the next hop, while the ICX works as DHCP server and default gateway for your home router.
I'm happy to receiving your feedback. Please let me know if this clarifies your concerns.