I have recently followed https://openwrt.ebilan.co.uk/viewtopic.php?f=5&t=129 as referenced by https://openwrt.org/toh/bt/homehub_v3a to install OpenWRT 19.07.8 r11364-ef56c85848 on a BT HomeHub 3A. The forum over there appears dead for years with unanswered questions also, so I considered that I may post here for some more generic assistance.
How can I use the WAN port on BT HomeHub 3A - #16 by savostyanov has the same issue but appears to have hit a dead end.
I find the LAN and WiFi to be working perfectly fine as expected, however the WAN port on the back is not recognised as an interface.
As you can see from the wiki pictures, there is a red ethernet port on the back of the device next to the ADSL line port. The ADSL line shows up but is not something I am interested in using, but the red port I believe is a WAN interface port.
ip a shows no interface related to this port. If I plug a PC into the port, the port is not dead, there is a link, but obviously that isn't too useful. dmesg shows no activity when connecting and disconnecting the port.
How might I proceed with identifying the port in the OS and configuring it?