@rpaulpen 

At the risk of stating the obvious, under SETTINGS   SITE   SERVICES you have enabled MESH ok (checked the box)?

It can take a few mins after power up for the device to appear as MESH adoption.

  @Philbert Hi, thanks for reply.  Nothing is too obvious at this point ;-).  

Yes, it's already clicked on. 

thanks,

RP

  @d0ugmac1 I believe I would have to decommision the 670 and reset all my ssid's, etc.  I do have users and devices running on the 670 so would prefer not to take that route unless it solve the problem. I guess there's only one way to find out.

  @d0ugmac1 Well, you train of thought was correct.  It worked once i plugged in the AC1200 and commissioned the Ax5400 as you suggested.  Thank you!  What can I do next to figure out the problem?

Thanks,

RP

  @d0ugmac1

Would totally agree, this sounds like the best course of action for you.  Ideally you would want your faster / newer AP as the root to keep the backbone speed up, it should be capable of handling the mesh in theory

  @d0ugmac1 Yes that fixed it.  Thanks.  Very obvious once I think about it but isn't everything eventually!

The problem I see here is that if I turn down the radio on the 670 to match the 1200, I assume the 670 will not work with a WIFI 6 environment eventually?  It's best to replace the AC1200 with an AX1800 rather than tune down the 670 to the 1200?

RP