thanks for information, i will try communicate also directly with Asus if they can add this feature to original firmware or if exist some other possibility to solve it
I switched from RT-AC68U to pair of RT-AX92U, but i didn't expected that Merlin doesn't support RT-AX92U yet :-(
Everything is working perfect, but it's not possible set "Custom domains with dnsmasq".
On RT-AC68U i set it according to...