I made this script for WireGuard in particular but it can work for OpenVPN if modified slightly.

Basically when the VPN service is running when you are in the office internal servers will NOT be accessible unless you turn off the VPN.

This script attempts to start and stop the VPN based on you location. If you are in the Office it will stop the VPN so you can access internal company resources but when you are away it will turn your VPN on.

Create a text file called WireGuard_Script.bat and paste the following into it and save:

@echo off
REM Currently pinging Google's DNS server
set IPaddress=
REM Enter the external IP of your Office LAN
set OfficeIP="Your Office External IP"
REM The name of the TunnelService
set tunnelname=Office
REM How many times you want to retry checking for internet
set retrycount=20

ping -n 1 %IPaddress% | find "TTL="
if %errorlevel%==0 (
goto IPCheck
) else (
goto wait

if %retrycount%==0 exit
set /a retrycount=%retrycount%-1
ping -n 4 >nul
goto networkcheck

nslookup myip.opendns.com resolver1.opendns.com |find /c %OfficeIP% >C:\temp.txt
set /p count=<C:\temp.txt
if %count% == 1 net stop WireGuardTunnel$%tunnelname%
if %count% == 0 net start WireGuardTunnel$%tunnelname%
del C:\temp.txt
ipconfig /registerdns
net stop WireGuard-Script

I then needed to register this script as a service so it would do it’s thing at startup.

NSSM is a great tool for making this happen.

Once Downloaded I put all the files in the WireGuard installation directory and then ran these commands:

"C:\Program Files\WireGuard\nssm.exe" install WireGuard-Script "C:\Program Files\WireGuard\WireGuard-Script.bat"
"C:\Program Files\WireGuard\nssm.exe" set WireGuard-Script start SERVICE_DELAYED_AUTO_START

Once Complete when you open services.msc there is a new service called WireGuard-Script with Automatic Delayed startup type.

I will admit the script is not completely reliable. It may have to do with the retry count possibly I have not tested or troubleshooted anything yet however most of the time it works well.