@Kevin_Z Thanks for the answer! I feel like we are all early adopters and beta testers in the wonderful world of WiFi 7! But I'm slowly starting to understand a few important things... One more...

@Kevin_Z Thank you for explaining it, it makes sense now. I didn't know about this hardware limitation for phones. The Intel BE200 adapter in my ASUS notebook works, uses both MLO lanes. Obviously...

@Kevin_Z OK, I also tested it with a Xiaomi 13T Pro, the result is the same. So it's the router's problem, not the phone's.

@Kevin_Z I have the same problem. BE550 1.0.11 firmware, Samsung S24 Ultra connecting to MLO SSID, but only to one band. The switching between 6Ghz/5Ghz OK, but the multi-band connection not working.