Netgear Genie on my C6300 firmware V1.02.19 has a bug in the address reservation logic.
The initial Lan Setup screen shows the reserved devices. In some instance when you press Add (to reserve a new address) you get the status bar saying Updating Settings and then an error message saying something like "server received no data" (like it expected to add an address when nothing was selected).
When this occurs, you can instead select any one of the devices listed (even though it has nothing to do with the new device to be added) and press Add, and the subsequent screen presents you with a list of all known devices and you can successfully add a device from this screen.
Another probably related bug is that it tries to update settings without anything to do (probably because nothing was selected from the initial list).
Finally figured out I could select any one of the devices on the initial screen to get past this, but not after an aggravating and useless phone call to your support line.
