Have been testing WAN connections from a 2865ac using WiFi (WAN3)

Since the router configuration uses the external AP's MAC address, this requires that the AP doesn't randomise its MAC address - otherwise the router can't re-connect.

The result is a solution that is really inflexible if using a modern mobile phone as the AP.

It would be great if this feature 
(a) Optionally didn't require the AP's MAC address to be static
(b) Supported configuration multiple APs on the same WiFi band

I have a work-around. Router WAN3 connects to an extender AP which connects to mobile phones.  Inelegant, but it works.