Is it normal that my users cannot connect to some websites that are not blocked by my firewall ?
We have always this message: Your connection is not private ...
Are you using Inspect on your HTTPS proxy action?
If so, have you added the firewall certificate to the web browsers of your users?
Use Certificates with HTTPS Proxy Content Inspectionhttps://www.watchguard.com/help/docs/help-center/en-US/Content/en-US/Fireware/certificates/cert_https_proxy_resign_c.html