I'm on current snapshot release, so I have the new DSA switch config thing.
The BT HomeHub 5A has 1xRJ11 port (that I use for ADSL) and 5 RJ45 ports, 4 yellow and 1 red.
The 4 yellow ports works with no problem, the red one (that I guess is used for WAN when you have an external modem and do not use the RJ11 port for internet) is like it does not even have power.
No logs are seen (with logread -f) when I plug something in the red port and inside /etc/board.json it does not even exist.
From the wiki I understood (not so much) that the red port has some issues because is not wired like the other 4 yellow ports and thus does not support some stuffs (like VLAN), but for my purposes I would just like to use it as a simple additional port, I do not care if I need to config a whole new subnet for it.
I'm feeling that I'm clearly missing something but I do not know what.
All I did was add 'wan' to the other ports in the br-lan.
I experienced issues with the original driver when using the wan port as an extra lan port and vdsl, but it has been working fine as a fifth lan port with the DSA driver. Not tried setting up a VLAN yet.
config device
option name 'br-lan'
option type 'bridge'
list ports 'lan1'
list ports 'lan2'
list ports 'lan3'
list ports 'lan4'
list ports 'wan'
list ports 'bat0'
Yes, as far as I understand the idea is to give ports in OpenWrt the same names as is printed on the outside of the case. And for the HH5A the red ethernet socket is labeled WAN... (the other's are simply 1, 2, 3, 4, but lan1 - lan4 is close enough). But that port 'wan' is not the same as OpenWrt's idea of the true wan device, which for a dsl modem probably is dsl0....
<=18.06.x and 19.07.x were using swconfig, as you see with the switch configuration in luci - master/ snapshots have migrated to DSA (the configuration is different there, as explained by mjs and moeller).