I have an Archer C5 configured in bridge mode, connecting to my fiber modem.  From the C5 I run a LAN cable to the Archer C6 which is setup in Access Point mode.   For now both are set up in "smart" mode, with the same wifi name. This kinda works, though I generally have to turn wifi off/on on a device to get it to switch to the nearest Archer, so I want it to use OneMesh as advertised on the box.  On the C5 it says there are no OneMesh devices on the network, and the C6 has no options regarding OneMesh at all.

How can i set this up?

I don't want to use range extenders, they are causing more problems than they solve, and I have the house wired up with LAN already.