What if I am not able to save changes in VPN configuration?

Explanation:  You may not be able to see the changes. Or the same configuration page may appear when you repeat the operation.

Action:  Ensure you click the Apply button for General Parameters of site-to-site or client-to-site and click OK in traffic rules/authentication rules before you click OK at the bottom of the site-to-site or client-to-site configuration page.