On the Virtualmin tab go to Server Configuration / Change IP Address
On that screen you will see where you can change your internal and external IP addresses.
Example: Lets say you were hosting at a provider at 47.5.225.39 but you are shutting down the online host to host it locally on your own network and that address is 192.168.1.100
All you would do is open up that panel I listed above and enter the 192.168.1.100 into the current ip address and then down on the external address you would click the button that says “same as real address” and that will do it.
@Gomez_Adams now you see when some one does not understand, meaning whole life on boat, then jump over and realized the one cannot swim at all as have no glue…you been there already.