I'm not very hopeful here after seeing similar old posts that were closed with no responses, but here it goes.

I just bought a BE900 and BE550 that I want to use in AP mode (BE900) and the BE550 as a satellite, wiith more BE550s as satellites to come if I can get this working. Everything was fine, both units meshed and were working. Then I switched the BE900 to AP mode and my BE550 satellite disappeared and the front of the unit just has an exclamation mark on the display now. Please don't tell me that I can't use this thing with the satellites in AP mode to extend my internet downstairs. Both new BE units are hardware v2.6 and are running the lastest firemware as of 12/13/25, both updated before I switched to AP mode. 

I have an older Deco AXE5300 mesh system in AP mode with 4 satellites attached, using the 6ghz as a wireless backhaul and it's served me well. I only updated to Wifi7 due to the Christmas sales on Amazon, the BE900 was only 320 after discount and the BE550, only about 135 after discount.  

I run a pfSense firewall appliance so my AXE5300 Mesh and my old Unifi Wifi5 systems operated in Mesh with satellites and never had issues in AP mode.