@Tony Hi Tony.
I'm referring to the setup of the VLAN number as per these instructions: https://www.tp-link.com/us/support/faq/2317/
I know that the VLAN number for the guest network can be set using a Wired backhaul. I'm using a wifi backhaul so I don't have the option to set the VLAN number for the guest network. I had read somewhere that, in the future, it may be possible. I was just asking if it's still on the roadmap.
Thanks.
--EDIT-- I should also add that I'm using my Decos in AP mode as I'm using an OPNSense router to do all routing.