Now I remember my reason for not wanting some shares to work across the VPN. We have a backup share where laptops automatically do backup at lunchtime (if they are turned on and on the LAN). The backup share is accessed by an automatic job on the client laptop. There are also other shares on the server that the ordinary user uses.
When they go to another office, they need to use the user shares remotely across the VPN. But when the backup job starts up at lunchtime, I don't want it to succeed - and saturate the VPN with a backup to their home site.
I don't think there is going to be a way to fix this with firewall rules or Windows server settings. Might have to think some more about making an DNS alias name for the server, making that alias only resolve at the home site, and making the backup job use that alias. Then it should fail when the laptop is away from its "home site".
Anyway - not a pfSense issue, but may be doable with a DNS Forwarder Host Override (extra name) at the home site.