ReadyNAS secure connection

https://community.netgear.com/t5/Using-your-ReadyNAS/Not-Secure-https-xxx-xxx-x-x-admin-Using-a-ReadyNAS-2100/m-p/1263939#M128078

https://kb.netgear.com/7003/Installing-a-Certificate-on-Google-Chrome-for-ReadyNAS-OS-6

The ReadyNAS use what is called a "self signed certificate".  When you run HTTPs, that certificate allows encryption, but the web browser can't verify that the NAS is really your NAS.  That requires a certificate that is signed by a certificate authority (CA).  The NAS isn't Netgear's - it's yours - so Netgear can't provide a signed certificate for it.

Options you have (in order of difficulty) are:

(a) just ignore it and click through

(b) attempt to install the NAS certificate as a "trusted" certificate on all your devices.  Details depend on the operating system.

(c) get a CA certificate and install it on the NAS

(b) is quite a bit harder than (a).  My advice is to click through the warning.  A variation is to use FireFox to manage the NAS - it will let you save a security exception, so you only need to click through once.