The L2TP-VPN server did not respond. My VPN was working fine and then I updated OSX BigSur and now I am getting an error every time.

Hello GreenRiver88,

You mentioned that you're receiving an error; to help us better assist you, can you let us know what the exact error message says? Is the message saying the server did not respond only, or are there any error numbers or codes in the message? That information will help us proceed.

Please also check out this link to ensure the correct process is being used to set up and connect your Mac to a VPN, so we can make sure there's not an issue there: Set up a VPN connection on Mac

Set up a VPN connection on Mac

To connect to a virtual private network (VPN), you need to enter configuration settings in Network preferences. These settings include the VPN server address, account name, and any authentication settings, such as a password or a certificate you received from the network administrator.

If you received a VPN settings file from your network administrator, you can import it to set up your connection. If you didn’t, you can enter the settings manually.

Thanks!