Using SSL certificate with Nav service - FQDN vs local

Hi,

I have an Nav 2016 service that runs with an untrusted SSL (Navhost1.dom.local)
Credential type Username.

Works just fine - but the clients needs to have the certificate imported I order to start and logon the Navision client/server.
On the Nav server the SSL needs to have the computername (Navhost1.dom.local) in order to start.

But what do I do if I want to use an globaly trusted SSL for example Navhost1.mydomain.com?
Do I need to rename my navserver and windows domain?

Have tried to use split DNS. Created an new zone mydomain.com with the host Navhost1 pointing to IP.
Does not work.

Can not find any info regarding this.

Best regards
Martin