Multiple IP's

If i have 2 Static IP ranges on my External and DMZ NIC's is there a way i can select or switch between IP's when i try to connect to openVPN?

I'm using VPN client to log into LAN for troubleshooting and if there is an failure or speed issue on External Interface (ISP) then i have trouble login.

Any options? :confused:

Additionally, Any way to install Open VPN client on a windows RT version?