wbs316
https://servername&
https://servername.domainname.com.auare not the same !
If you want to avoid self signed certificate errors, you have to use the URL that matches the certificate installed in your browser.
Your second recent post demonstrates that.
If you do not want to maintain hundreds of workstation browsers & install/upgrade your self signed certificate whenever it changes (due to domain name reconfiguration on the server etc), then the answer is to buy a commercial certificate & install that on your sme server. They are relatively cheap these days.
The commercial cettificate provider will be included in root certificates issued to web browsers, & as long as users update their browsers periodically, then your certificate provider will be included in the root certificate, thus they will not receive errors.