Isn't the whole concept of a VPN 'to access internal services via their internal address' ? as the VPN client essentially puts your device onto the internal network ? At least that's how I've always thought of it. Happy to be corrected.
Wonder if the BI client, in making its decision on whether you're on an internal or external network is not doing it the same way on the 2 device types,.. so maybe on Android it 'thinks' its on LAN by the way that OpenVPN maybe doing things,.. and hence this goes to the LAN address ? Dunno, just thinking out loud, while I'm waiting for something to finish. Curious to see what happens if you put some other arbitrary address in on the Android WAN address to see if it still works ?