Question about Philips Hue Wandschalter Modul

Hello everyone, I'm getting desperate... I've installed two of these modules for four buttons. However, as soon as I insert them into the flush-mounted box and screw the switches in place, the Hue modules are no longer accessible, even when I open the modules up again! Each time I have to reset the modules to set them up again, which often only works after several attempts. Yesterday it took me over two hours. The bridge is located almost directly diagonally opposite (approx. 2.5 metres away), but still keeps losing the connection. Has anyone had similar experiences? Could it be due to defective modules or is there a solution to this problem? Is the range a problem?