BT HomeHub 3A running OpenWrt - WAN not working?

Hi there,

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.

From SSH, 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?

Thanks!

Looking at the post by savostyanov that you linked it appears as the WAN port is unused and he made changes in order to use one of the LAN ports ( quote from his post [LAN1] = port 4 ) as WAN.

According to deviwiki there are different ethernet chips and I would presume that the PSB 50810 is not supported and that is why you would want to remap one of the LAN ports as a WAN:
ETH chip1: Lantiq PSB 50810
ETH chip2: Lantiq PEF7071V
ETH chip3: Lantiq PEF7071V

Also I've found this - https://openwrt.ebilan.co.uk/viewtopic.php?f=5&t=267 that confirms my suspicions

Hi there,

I do indeed see the splitting of the 4 port switched LAN interfaces into the WAN and 3 LAN, however this is not a solution I really wanted, wasting a dedicated port for such a purpose.

It would indeed be nice if it was possible to get the port up and running, seeing as these old hubs are quite common in the UK as old parts, and I have two,

Thank you for your further research and technical information, it is much appreciated