@Dr1T If you don't have any Internet connection configured here: you'll have onlly "No interface" option in this drop-down menu.

@Tpoo56 If you forgot your router admin credentials you have to reset the router to its factry defaults (press reset button for about 10 seconds) and re-configure from scratch.

@g7styles Try this procedure for router recovery - Method 2.

@ADDolatabadi I would reset both RE200 to their factory defaults. Add the first one to the Onemesh then turn it off. Add the second one, turn on the first one and check if there's any improvement.

@Volkan_Akkus_TR This screenshot is just an example, open your modem and you'll see your actual values. These parameters can change in real time.

@Kostanthsntoysl Follow the hyperlink I posted and choose an appropriate Deco unit to add and extend your wireless coverage further.