Secure log-in gives warning?

Why is it that if I check the "Secure sign-in" option for my QNAP TS-453mini NAS I get a Windows warning that the site is unsafe and if I over-ride the warning to log on, the address bar shows a "Not Secure" warning. The warning says that the security certificate points to myqnapcloud.com.
How do I correct this?
Thanks, Geoff

Hello, I had similar warnings on my synology, and following some advices found online (don't recall the website) I managed to fix it. Usually the certificate covers something like www.mydomain.com and if you connect with an address like 192.168.1.x the browser will mention that the certificate does not match the certificate (and it indeed doesn't). I assume that this is the issue you are having, something close enough.The tips was to add a subdomain like lan.mydomain.com in the certificate and to have the DNS server on my home network resolve this lan.mydomain.com into the 192.168.1.x , then I use the lan.mydomain.com name to connect to the NAs on my local network. As the lan.mydomain.com is included in the certificate it works. I am using let's encrypt for the certificate, but I am using the DNS01 method as the port 80 isn't accessible. Hope this help. Regards, Stephane

Thanks Stephane, I'll try that.Geoff