orbilogin.net stop working after Mac OS Monterey upgrade

Any modern browser will show certificate issues - simply because it's not possible (Netgear has done this in the past) to include the real signed certificate and the private key on every device. All you can do is find the way to work around, like accept the certificate, and continue to the device local Web UI. 

Alternate, simply try the simple http as you are connecting on your local network only anyway. 

Based on the Monterey beta comments, people have moved to an alternate browser (like Chrome) to access servers with self-signed certificates.

Challenge Apple on how their securitywonderheads expect https to work nowadays on small devices like local stuff... Yet another new nightmare following the random MAC garbage (apple says private MAC) causing issues allover the networking world - and simply not required on your own personal/private/business network.

Regards,

-Kurt