Incorrect Password Error on Only One of Many Devices

Hello everyone.  I tried searching the database but couldn't find any posts that directly relate to my issue.

In total, I have 24 devices that historically connect to my xfinity network.  Yesterday, just one device, a litter robot, simply disconnected with no prompting whatsoever.  The network wasn't changed.  The password wasn't changed.  There were no power outages.  The remaining 23 devices all remained connected and are still that way now.  However, when I attempt to reconnect the litter robot, I receive an error that the wifi password that I entered is incorrect.  Rest assured, I attempted many times and the wifi password that I am using is correct.  Thinking that this was certainly a litter robot issue, they informed me that it was an xfinity one that that something on my router was preventing the litter robot's authentication.  I have been determined them to be correct as I connected the litter robot to a hot spot on my phone and it connected without an issue.  Afterward, when I tried again to connect to the xfinity, the "incorrect password" manifested again.  I then connected the robot to separate hot spot and, again, it connected perfectly.  No success on the xfinity router after that though.  This is certainly an xfinity problem and not a litter robot one.

Things that I done so far:

• "Forgot" the litter robot in the router's connected device list (it's still in the "forgotten" state as it won't reconnect to be "known")
• Rebooted the router.
• Rebooted the robot.
• Uninstalled / reinstalled the litter robot app.

Nothing has worked.  Online searches have shown that other people have had similar "incorrect password" issues with devices other than litter robots as well it's not like this is strictly a litter robot thing.

Does anyone have any thoughts on this issue?  I will contact xfinity support when I get some time but thought I would throw this out there for other people who are experiencing this issue.