I tried this both with ASUSWRT-Merlin TUF-AX5400 3004.388.9_2-gnuton2 and ASUSWRT-Merlin RT-AX56U 3004.388.8_4 with Diversion 5.4.6 (+Skynet 7.6.5 if it matters), DNS Director is enabled with Global redirection set to Router. I enabled the large filtering (https://big.oisd.nl/dnsmasq2) plus one...
TUF-AX5400 is supported by gnuton’s fork of Merlin: https://github.com/gnuton/asuswrt-merlin.ng
May not help with extending the other guest networks, though, not sure.
Power button on one of my N66U broke recently. Fixed with the toothpick solution.
I was actually next to it when it happened. Was surprised why internet went away. Then I saw all LEDs are off, so I thought plug came off the socket or something, but that didn't work. Then I tried to fiddle with...