Certificate for 2304

Certificates that will pass the test Chrome uses to say it's "safe" cannot be assigned to a  local IP address.  So no NAS on a home system will meet that test.  Most instructions for importing self-signed certificates for Chrome are out of date and will not change the situation.  The only thing you can do is to actually read the warning, insure you have the right IP address, and click through the "not safe" warnings.

What Chrome is warning you about is that the site may be a fake.  If you are performing an operation on your local network, that's not really likely unless you've put a really big hole in your router.  If you have made your NAS available over the internet and are accessing it that way without a VPN, SSH, or some other security means, then I suppose it is possible sombody is masquerading as your NAS, though It's also unlikely.

It is quite unfortunate that Google, Microsoft, and the lot have chosen to not give a local network exception to this warning, or at least tone it down.  It is likely out of fear of being sued if somebody ignored all reasonable protections to their network and there was something compromised.