These are being used as gateways for CenturyLink Fiber networks. They plug into an ONT (despite having an SFP port), have AX radio. I got one today off of ebay, hooked up a serial console and got a boot log, but no shell. The magic for getting a u-boot prompt wasn't obvious. They run pretty warm, using a 12V 4A power supply and have large heatsinks on the main board.
I'm also curious about this. I received one (to own) from Centurylink for signing up with their fiber service. I'm currently still using an Archer C7 with OpenWRT so it would be nice to upgrade to wifi 6, but only if it can eventually run OpenWRT. I had a read through this thread and it doesn't seem likely. It seems the chip was abandoned and I never got a reply from that one guy who was investigating getting support for it again.
I have a C400XG, May I ask how to stop autoboot in order to use command line of uboot?
I found out a way. it's to downgrade to FW version CGX002-00.01.86.02.bin.
my currect FW version is CGX008-01.03.78.00.bin.
Got a link?
Fwiw, I requested CenturyLink provide the source code for open source components of the C4000XG firmware and received it about a month ago. You can find it here: https://personaltelco.net/~russell/C4000xg_oss_release_01.03.tar.xz