Missing Devices from R6400v2

While I was connected to the router with my iMac, via ethernet cable, I changed the passwords.  I then entered the new passwords on 3 of my devices.  Those 3 devices are currently connected to the router.  I opened the Nighthhawk app, and the Device Manager says there is only ONE device connected to the router.

On another post about another problem I mentioned that there was an unknown device on the Device Manager list.  At that time I had 6 known devices on the list, and one unknown device.  

I did a firmware update last night.  The number of known and unknown devices was the same before and after the firmware update.  After changing the passwords this morning, entering the new passwords on 3 devices and connecting those devices, the Device Manage says there is one known device connected, not the 3 that actually are connected.  It's possible that the unknown device is still connected, but if so the Device Manager is not seeing it.

My knowledge is limited.  I have spent enough time on this already.  I do not want to do a factory reset.