odd issue --- how to point the default ip address url to a subdomain vhost?

I have a customer who has a static ip and we are setup to use nextcloud as a vhost (nextcloud.yourdomain.com) all works accessing this - but incase the internet goes down they want to be able to access it interally by the local static ip (10.0.1.45).
I added 000default.local and indeed http:/10.0.1.45 brings that up.
but I want to redirect it to the subdomain vhost (nextcloud.yourdomain.com) - and that does not seem to be obvious. so that http: (or better https://10.0.1.45 brings up nextcloud.yourdomain.com
I guess we could symlink it or edit the vhost and change the root path, but these are both rather nasty and brutish and ispconfig will want to write back over the vhost at some point anyway.
is there a nicer way?

 

Couldn't you simply add "ServerAlias 10.0.1.45" to the "Apache Directives" field in the options tab of the vhost?
And of course delete your custom vhost for the ip.