Shouldn't. From what I have read and after speaking to tech support - it has the 2.4 transceiver chip in it, so it can't connect to 5. I don't know how much I believe that the problem is in the router, as the controller would only be able to connect to the 2.4 on the router. I imagine there could be instances in the software of the router that could prevent connection, but I don't understand the point of that. You might as well have two separate access points. I bought the extender only because our outdoor kitchen is farther away and I there was no way to tell how strong the signal was from the controller.
Have you flushed the cache and files for the app, the uninstalled the app - then reinstall?