Trying to figure this out on my own but struggling. I have a Netgear Nighthawk X4S AC3200 (C7800) that I purchased in the US while using Comcast. I had it shipped to NZ, but NZ ISP largely use an Optical Network Terminal (ONT) meaning the Coax cable cannot be used on my router/modem combo. Instead the ONT converts the data to ethernet and plugs directly into whatever router/modem you have.
To address this, I had hoped to use bridge mode and just use it as an AP, however, Netgear OS does not have a bridge mode function built into its software. I tried plugging the ethernet cable in from the ONT into port 1 of the C7800, but that too fails. The C7800 does not see port 1 as providing it with internet. It appears to only function with the coax plugged in.
So I turned to OpenWrt in the hopes of using the C7800 instead of the wimpy existing hardware provided by NZ ISP. However I cannot find the exact model of my device to flash the firmware to OpenWrt. I found that version 19.07.7 supports a Netgear Nighthawk R7800 which is similar to my Nighthawk C7800, but I didn't want to just install without checking here first. Can I install OpenWrt on my device, even though it isn't explicitly supported?
Also, in the event I need to go back to Netgear OS to try and sell it back in the US, how can I get the device back onto Netgear's OS? According to Netgear's own documentation for the C7800, "Firmware upgrades are pushed down by your ISP.". Additionally, Netgear's firmware version page doesn't have a way for me to download the firmware should I need to roll back.
I'm just trying to either use the router/modem in bridge mode or set it up to funnel traffic from ethernet port 1
Can I use OpenWrt 19.07.7 using software for Netgear R7800 despite having a Netgear Nighthawk X4S AC3200 (C7800)?
Can I use OpenWrt to either put the C7800 into bridge mode OR have it route traffic from port 1 instead of only the coax cable?
How do I get the firmware back to Netgear's OS in the event OpenWrt does not work for the device?