I am running the OS X VPN Service in a mixed OS X / Windows environment and have hit a snag. I configured / setup the VPN Service to use L2TP, I opened the necessary ports, etc. I know that I configured / setup the VPN Service properly because I can consistently connect to it using my iPhone 5s without any problems. That said, I cannot get my Windows PC to connect to the VPN Service no matter what I do...I don't know whether the issue is that the Window's 7 VPN client used IPsec, I don't know whether the issue is my settings (which are attached as screenshots [with the IP address obviously changed] where I have entered my "shared secrete" in the preshared key field), or something else). Would greatly appreciate everyone's assistance as I desperately need to get this working.