Thanks for the link.
Although the issue and solution is useful, it doesn't quite give me what I am looking for.
The link above has the following:
"so i noticed ssids become unstable after having more than 2 per band on 2.4ghz or on 5ghz, this means you either have to sacrifice the guest wifi for the custom network you can trust me this is the easiest way, honestly i doubt guests need 5ghz"
This approach will not give me what I am looking to achieve!
Many of my IOT devices only operate on 2.4Ghz.
I want my IOT devices to have a new SSID on 2.4Ghz and to have a different subnet (192.168.30.0/24) to that of the LAN (192.168.10.0/24) and the GUEST (192.168.50.0/24 on both 2,4 Guest and 5Ghz Guest) interfaces.
I managed to create two new bridges and interfaces (with different subnets) to manage a single VOIP telephone on LAN4 port, and an Xbox on LAN5. I got both to work as expected with new subnets and firewall rules to ensure isolation from the LAN interface (which has LAN1, LAN2, LAN3 plus the two RA0 and RAX0 wireless devices).
Based on the 'success' of the VOIP and XBOX interfaces (and new bridge devices), I tried to do the same with 2.4Ghz ra0 but I could not make it work. I could not figure out why the 'GUEST' interface showed it was associated with br-guest bridge device and yet this device is not in the list of devices in the Interfaces tab, and when looking at the config of the GUEST interface, the 'Device' on the General Settings tab is 'unspecified'. On my VOIP and XBOX interfaces, I associated the new bridges for each (br-voip for the LAN4 port, and br-xbox for the LAN5 port), but I cannot find a way to create a wifi bridge and get the ra0 to work as I want with a new subnet.
It would be extremely helpful if some instructions could be given to help me. Just as a test to prove the process, if I disable the 2.4Ghz Guest, what is the process for me to add a new radio, with a new IOT interface and say an associated br-wwan0 bridge (a copy of the br-guest bridge) to allow my IOT devices to connect on a new subnet (different to the GUEST subnet) and be isolated from the LAN?
Many thanks.
EDIT:
I stumbled across this post.
"Show different subnet clients in gui"
Given the additional issue of the Client list not showing connected devices which have connected via a custom bridge (i.e. the VOIP and XBOX do not show in the client list, but they do in the LUCI screen), I suspect the issue I had in not getting the custom WiFi to work is likely associated with this.
Does this imply that I can only get an additional custom WiFi SSID through the Luci interface and that none of my IOT devices will show in the GL GUI? I hope not! I've just spent €140 on my first GLiNET router!