Hello Cybermaster:
I suggest you use redirect to do it.
PATH: Server.app > Websites > The site you want to edit > click the icon has pen
> click the edit button which row is Redirects
if you see the default rule already in there which meaning "This Website redirect to SSL Site" then just click pen icon to edit
if you don't see anything in the pop-up window then you click "+" button to add new one.
Change first drop down box to "This Website".
Change second one to "Other Website...".
Enter your url to the third box.
After you finish your settings will look like this >

Final step just click "OK" button to save it and restart your web service by switch off and on and it should be work.
Hope this can answer your question.
I would like to answer about your other related questions.
All the best & farewell 🙂