When you assign OpenVPN as an interface there will be an additional tab on firewall rules where you need to allow traffic.
Not sure if you then need to add static routes for this OpenVPN interface - what in general is done by the OpenVPN server.
EDIT: I tried adding a rule to the new tab that looked exactly like the one on the OpenVPN-tab, but as soon as I assign an interface to the OpenVPN (I don't even know what this actually does...)
I cannot get any access to my LAN.
This is way above my level of knowledge about computer networking, I've been looking at the rules and I frankly just don't understand how it works.
Plus I couldn't find something in the menus about "routes"....
I was thinking it worked just like an extension of your LAN, I was so wrong.
I've been searching the forums for someone with a similar problem where I could find some help, but I couldn'r really find something....
EDIT2: Found where you could add routes but it only looks like they apply to the WAN...