Archer BE550

You can't mesh them together, as they're not compatible. Even if you give the WiFi networks the same name, these will still be two different WiFi networks, and you won't be able to seamlessly roam between them. There is no actual reason to keep your BE550 as one of the Decos can be your main router.

Yup, similar issue with my BE550. Smart Connect isn't as smart as it should be! :D When I previously had Smart Connect enabled, my Pixel 9 when at long distance, would not drop down from 6GHz or 5Ghz to 2.4GHz automatically. Tether app would indicate that my Pixel 9 had a weak signal on 6Ghz or 5GHz

Just to add to this the router refuses to acknowledge my laptop and use universal plug and play, even tho I've spent two days on this with Gemini trying to make it work. The old Xbox walked right in and used universal plug and play on 2.4ghz with the Tp Link Archer BE550 9300 no worries. It worked f

I had nothing but issues with MLO on my BE550 Pro. I also suggest turning it off entirely as there is not much real world benefit to client devices at the moment.

Got disappointed with openwrt because an pretty recent router I had (deco m5) was not officially supported, had to download "alternstive release" which had some issues, and the other router I bought (tplink be550) is still not supported.