First of all, my router is an Archer A6 (not A7) but such model is not in the dropdown list.
The router works fine, except for one major problem: when a wi-fi client connects the DHCP will occasionally serve an address on the 192.168.2.x range instead of the expected 192.168.0.x range. That happens randomly. When the problem happens, the wi-fi client will not appear on the list of connected clients as if it didn't exist. On the client side, however, the client will acquire a 192.168.2.x address and a 192.168.2.1 gateway which are of course wrong and will not work correctly.
After disconnecting and reconnecting repeatedly the correct address range will eventually be served.
This happens on different iPhones as well as laptops and also other connected devices.
Any help is really appreciated