OzarkEdge
Part of the Furniture
First he got 66U_B1 not 66U and B1 is same as 68U and supports Aimesh!
Second he uses WIRED backhaul, so there is no need for any Wifi at all to mesh them!
He has a 66U that support AiMesh... the build ID is irrelevant to my observation regarding no Smart Connect support on any and all 66Us.
Despite using a wired backhaul, there was some earlier notion that all radios still need to be ON and within range to permit adding a node. For lack of a better idea, it's worth considering and easy to verify.
OE