why not access jellyfin From House B over VPN with House A

At man ment I do it with + adresses instead of alias. It works also.

Meanwhile I do not lile it anymore, that the caldav calendars are fully separated. Its not possible to have the flexibility I need for family management.

Thanks for the hint. Long ago I also used syncthing. At that time it not fit my needs. But in this case it may is a possibility.

Any best practises for excluding files in Home for syncing like .cache ?

As far syncthing does not come with a vfs.

All family member I support and provide with services use a Laptop. They are connected over wireguard. Solutions that depends on Network connections will not work.