I love my small Eero setup, one Pro and one Beacon. 

But recently I couldn't d figure out why my becon went from sharing some of my 16 devices to only one. Finally called, spoke to Darius and just couldn't figure it out. I thought maybe there's a cache I could clear but just rebooting should redistribute. Nope. 

It suddenly dawned on me, I had added a wifi smart switch to same outlet the beacons plugged into. This is an Eero only thing. Only Eero has the beacons rather than a plug or plug in power supply like Google or TP-LINK. The smart switch being so close to beacon overwhelmed the beacon. Moved beacon away from smart switch to another outlet maybe 3 feet away and the beacons back to handling 6 of 16 devices. 

So, if you have any smart wifi switches, keep away from beacons. Don't use same outlet as beacon.