Can't connect to SMB shares using OpenVPN

Question

I've managed to set up OpenVPN server on my ASUS RT-AC66U router at home that's using
the Asuswrt-Merlin firmware. It's set up using a TAP interface and I've installed the OpenVPN client at a remote machine. I can connect through the VPN just fine, ping machines on my local network, access web servers and even RDP to them but I can't for the life of me connect to any of the SMB shares on my computer running Windows 7. When I try, here's the message I get:

When I try to access a hidden share, Windows just complains that it can't access it:

Has anybody ever got the above message The account is not authorized to log in from this station. and is there way to get these shares working through OpenVPN?

Because I can ping machines, RDP to them, etc. this leads me to believe it's a Windows 7 configuration issue (and not an OpenVPN issue).

Edit: Windows firewall is completely turned off.

Solution

After some more testing I have managed to figure this out. I ran the client on another remote computer and the SMB shares were working fine, so I knew it had to be a problem on my local machine. After some Google-fu, I was directed to some local security policies. If you run "Local Security Policy" under Administrative Tools, there is a policy under Local Policies -> Security Options titled "Microsoft network client: Digitally sign communications (always)". I set this to disabled, and ran gpupdate /force from the command line and viola, it worked!