@Marvin_S Hi Marvin,

Thanks for your prompt reply.

To reiterate:

1. The XE75 Pro is connected in AP mode to the router via Ethernet cable
2. One M9 Plus is connected in AP mode to the router via Ethernet cable
3. The other two M9 Plus units are connected in AP mode by wireless backhaul, i.e. no Ethernet connection

Personally, I think that only the XE75 Pro  - which is designated as Main in the mesh network by the Deco app - should be connected by Ethernet cable to the router, and the 3 M9 Plus units should be connected by wireless backhaul, i.e. no Ethernet connection.

What I was in need of is confirmation of this supposition. I will check out the link in your reply, and get back to you.

Once again, thank for replying.

  @SteveWex 

Thank you for your reply. Thank you for the post link. Most enlightening.

My orginal intent was to create a new network with 3 XE75 Pro units, and sunset the M9 Plus network. Then I read the bit about mixing devices, and added an XE75 Pro unit to the M9 Plus network. From there the rest is a history of woe.

I'll tinker a bit more, starting with having only the XE75 Pro unit connected to the router, and see what happens. I'm hoping to make it through to spring before I set up an XE75 Pro only mesh network. Beyond that, I'll take your advice and, come the summer, shell out for a different brand.

  @SteveWex 

Addendum to my earlier reply.

This afternoon things went from bad to worse, with 2 out of the 3 M9 Plus units going off line. So I bit the bullet and rebooted the XE75 Pro unit. At the same time, I removed the Ethernet cable connection to the router from the adjacent M9 Plus unit, before rebooting that as well.

Very quickly, all 4 units in the mesh network showed solid green.

Four hours later, and everything is still green across the board.

Now cynical me says that it is only a matter of time before things degrade back to red.

That having been said, I still intending to follow through, based on your advice.