Got a three-pack of Deco XE75 Pro to start upgrading my home network from a hodgepodge of old wireless and wired equipment.

My house has three levels, two floors and a finished basement, and we need wireless and/or wired 1Gb Ethernet on all three levels.

The cable from the ISP is only available on the second floor, so the cable modem is in my office and I put the main Deco unit there.

(Let me say up front:  I *cannot* run Ethernet cable all through the house, or really anywhere, to use a wired backhaul.  Or to run coax to relocate the cable modem (which I could then also use for MoCA.)  If I could, I wouldn't need more than my two current Ubiquiti AP's for wireless, everything else would be wired.)

I added a second unit on the first floor and after it showed some reluctance in connecting it now works fine.

Tried putting the third unit in the basement, almost directly under the one on the first floor but a fair distance from the main unit two floors up.

The basement unit connects sporadically and is extremely location dependent.  Then I noticed thet its backhaul connection is going to the main unit in my office, not to the closer second unit that's right above it on the first floor.

Is this how the Deco XE75 Pro mesh is supposed to work, i.e. as a star configuration with every satellite's backhaul going direct to the main unit?

If so that's pretty useless.  I was planning on putting a total of six satellites scattered all over the house on all three levels, some units a significant distance vertically and horizontally from the main unit.  I can't do that with a star configuration, I was counting on satellite-to-satellite backhaul to make this work.  (I understand that the network speed degrades with each hop.  I'm not concerned as the units far from the main one won't be supporting high speed/high capacity usage.  They just need to provide reliable connectivity to simple, mostly 2.4 GHz devices.)

I noticed in some of the troubleshooting instructions that it says "bring the unit (that's failing to connect) close to the main unit *OR* one of the other satellites".  Which seems to imply that it's not just a star configuration.  But it doesn't appear to work that way in real life.

Am I missing something - a setting, or something else?  The only setting I changed from default was to set the 6 GHz band to dedicated backhaul (which makes sense here since I have no 6 GHz capable client devices, and the 2.4 GHz and 5 GHz bands are pretty crowded with neighbors' traffic.)

Any advice would be greatly appreciated.  I'd hate to have to return all this fine equipment because it won't work in my situation.  Thanks!