R6400v2 - Dashes under SSID Column in Genie/no internet connectivity

I have an R6400v2 whose firmware is up to date (checked through the Genie.....says there is no new firmware). Just yesterday, certain wireless clients were unable to access the internet, but were connected to the wifi SSIDs (both 2.5 and 5ghz). No changes were made to either the clients or the router.

Those unable to access the internet are all Apple devices, however I have a Macbook Pro that is not impacted by this. When I look under the Attached Devices tab in the Netgear Genie, under the SSID column, it simply shows 2 dashes (--) for those devices that are expreriencing the problem. For those that are able to still connect to the web, they have the SSID listed in the SSID column for that row.

I have reset to factory settings, and that fixed the problem for about 10 minutes until it came back. The impacted devices work fine on other wifi networks, so it is not the devices.

Ideas?