@fdsjfhjkds 

Usually when we connect or join a new network, we will need to select the location or type of the network including home, work or public.

If you select public network, your PC will be hidden from other devices on the network.

By the way, how about pinging a wired PC from a wireless PC? if it doesn't work either, you'd better disable the Windows Firewall for a try.

  @fdsjfhjkds 

I can't make this any clearer. 

With my Netgear Nighthawk R7000 in place, everything works. Pings, RDP, etc. all work perfectly and as expected.

Replace the R7000 with the AX10000 and change nothing else. Pings stop working. RDP stops working.

Logically, the thing that changed is causing the problem. That's the AX10000. Somehow it is preventing basic low level networking functionality. 

I have no idea why and predictably, neither does TP-Link Support. Asking me where I bought the device and what the make and model of my PCs are reveals its own story.

No matter. 

The AX10000 is now back in its box and heading back to the retailer.

Should have stuck with Netgear. I have never had a problem with their routers before.

No further replies needed. Thank you to those who viewed this post and replied. Case closed.