I have recently received residential FTTH from a provider. To use the service I received a Zyxel box that works as an all-in-one solution offering both IPTV, VOIP, WiFi (802.11ac Wave2) and routing capabilities. The box has a fiber port and the fiber cable enters the residency and connects to that port through a standard connector.
The problem is that this is a very locked down box and is completely managed through the ISP customer site. It offers no local web interface, telnet, or SSH. I want to try and see if I can make it more useful by getting OpenWRT/LEDE on it. I took it apart and found a serial port populated which seems to be standard for Zyxel. It seems to use the Lantiq PXB 4389-720 (GRX330?) and I see references to wave300 and wave400 which I suspect might be the WiFi. Now given that I have access to the serial port I can probably start playing around, but before I do so I would like to make a backup of the current state since this is a rented box I might have to return at some point and would have to return it in the same condition it came. Any advice how to proceed from here? Can I dump the current memory somehow?