@p1r473 there is a main discusison thread for YazFi where people discuss issues with YazFi 4.x:
v4.4.4 Updated 2023-11-26 Feature expansion of guest WiFi networks on AsusWRT-Merlin, including, but not limited to: * Dedicated VPN WiFi networks * Separate subnets for organisation of devices * Restrict guests to only contact router for ICMP, DHCP, DNS, NTP and NetBIOS * Allow guest networks...
www.snbforums.com
As Rmerlin explained in the Asus-Merlin 3006.x threads, addon scripts likely have to be tweaked or fixed to support the Asus-Merlin 3006.x firmware.
The developer of YazFi (Jack Yaz) is no longer taking an active roll in developing YazFi or YazDHCP. As such it is unknown if any fixes or changes will be made to YazFi (and or YazDHCP) to support the 3006.x firmware base. Another user
@Martinski has done some tweaking of YazFi, but I don't know if they indicated the willingness to expend any possible time and effort to make YazFi work with the 3006.x firmware.
Guest Network Pro does many if not most of the things YazFi did. I found that I had to use the Custom Guest Network Pro option to configure it the way I wanted, and even then ran into some issues with Guest Network Pro. That specific feature likely will need additional fixing by Asus going forward. The few preset Guest Network Pro options for things like IoT just didn't work for my needs and were not very configurable.
Check each of the setting pages for Custom Guest Network Pro to see if you can change or disable the DHCP server. From what I remember when playing with 3006.x firmware on a RT-AX86U Pro there was an option to tie the Guest Network Pro clients to the main LAN DHCP server (which caused me issues). Maybe there is an option to configure your own DHCP server for Guest Network Pro clients.