Can't help you with that one - mine (2926ac) doesn't do that. Currently I don't have any wifi devices connected to the router (apart from an Android phone connected as WAN2, but that doesn't show in "Connected devices") as I now only use the mesh of AP903s, but when I did have some on both 2.4 and 5 GHz I don't recall that behaviour.

Interestingly, my "LAN Connections" line shows that nothing is connected, not even the PC on which I'm viewing the dashboard