Using Server 2012 R2, I am able to successfully VPN and access network resources (Windows 8.1). A friend of mine, using Windows 10, can also VPN but cannot access any network resources. My server is RRAS and everything else. The server isn't joined to a domain. My server can ping my IP, but not my friend's. RRAS hands out the addresses (doesn't use DHCP).
I used to let RRAS allow DHCP, but strangely it started sucking up all available IP addresses.