Nope, I never did. I bought two UniFi Access Point WiFi 6 Lite devices and have wired the first in to replace an ASUS repeater elsewhere, which has worked better for WiFi roaming. The remaining UniFi AP will replace the ASUS device that is the topic of this discussion. Sure, wiring the ASUS RT-AC66U may solve the WiFi repeater related DHCP issue, but I've had enough of mixed brand WiFi bits and pieces. The UniFi Single-pane-of glass will simply be less headache to manage a proper mesh.@GreyGoose Did you ever find a solution to your problem?
I have the exact same situation with iOS devices (15.1 and 15.1.1, not tried 15.2 yet) not being able to connect to a repeated WiFi using DHCP - static IP works just fine. There is a slight difference in that I have a RT-AX55 (3.0.0.4.386_45934) connected to the UDM (UniFi OS 1.11.0 and Network 6.5.55).
macOS 12.0.1, Win10, Win11 and a couple of different Androids work just fine.
Good luck and please post if you solve it!