Orbi 6 Satellite Out of Sync - Wired Backhaul

Had the same problem with my RBK853 (RBR850 +2 sats), but the problem was self-inflicted since I was trying to salvage my old RBS50 satellites to add to the new RBS850 setup.  When first setting up, the new RBS850's synch'd up to the RBR850 router lickety split without even trying.  I then realized I needed  2 more satellites for proper coverage but not enough to fork out another $500 for a pair of RBS850's So, with great determination, and reading a handful of documented but unverified successes, I attempted to synch a pair of RBS 50's from my previous Orbi RBR 50 setup.   After hours and hours of trying to synch the old RBS50 satellites wirelessly to the new RBR850 router (factory resets, FW updates, power cycling entire network, etc) I got the constant red halo on both sats, and ultimately caved, deciding to just use the old kit (RBR50/RBS50's) as a wired access point with same SSID/PW as main 850 router .  Well that created conflict and an overall performance hit, oddly enough due to the old RBR 50 router being unintentionally recognized and served up as a 3rd satellite by the new Orbi RBR850 at the expense of the 2 RBS50's  being ignored (as in, invisible).  So to avoid going down that hole, I was resolved now to just creating a 2nd wired network (different SSID, but same LAN to be managed by main router.  But after unplugging the old RBR50 Orbi router, with its 2 satellites still plugged and wired via ethernet, I noticed even without ever successfully synching them, they were giving me a great signal (wired) on my phone, they were showing up as recognized satellites albeit "out of synch" but all the local wireless devices were connecting wirelessly thru the 2 wired RBS 50's, with the same fast speeds as when I was next to the 2 newer satellites close to the main router.   So I don't know what the right answer is anymore , but an old pair of RBS 50's wired in and yielding the same speeds as the two RBS 850's makes the whole obligatory process of wirelessly pre-synching an afterthought.   I only wish I had been told.