Finally got my wifi-7/MLO network stabilized. I now have only 5GHz. and 6GHz. bands on my main network, and 2.4GHz only on the IoT wifi-6 network. I do have WPA2/WPA3 for my main (wifi-7/MLO) network, but as usual I'm sure that 6GHz. is using only WPA3. The Network page shows wifi-7 and MLO for my main network, so as far as I can tell using WPA2/WPA3 doesn't affect MLO. All my devices, except security cameras the HDhomerun, electric blanket, smoke detector, internet radio, etc. are on the main network, and everything's finally peaceful and happy. When I had both a 2.4GHz. IoT network and 2.4GHz. also on the main wifi-7/MLO network, it just fell apart. That's why I've taken the 2.4GHz. band off the main network. While I'm not using AiMesh at this point, I do have a wifi-6 router in repeater mode (for the security cameras, doorbell, etc.) and another wifi-6 router in media bridge mode (for the HDhomerun), both connected to the IoT network. All routers and devices are running well.
Been up for over a week now, a new record for me and wifi-7 using MLO *smile*. Just thought I'd share this in case it helps anyone.