Satellites stuck on config sync

With RBR50 in AP mode 3 of 4 satellites are stuck in config sync backhaul status.  My ISP is Comcast/xFinity and I'm using their gateway.  It's worked fine in the past.  The one satellite that connects ok is an RBW30 on firmware V2.5.04.  The other satellites and the router are on firmware V2.7.0.70.   I've spent hours with Netgear Support and have done multiple reboots, factory resets of everything, setting up each satellite one by one, wired sats to router, etc, etc.  All of the satellites connect fine if router is in Router Mode but then of course there is no internet connection - once the router is switched to AP mode, internet connection comes on but 3 of the 4 satellites go into "config sync".  I'm about to toss all of this Orbi equipment in the dumpster - please help if you can.  Thanks.