UTM 9 and NOD32

Question

Hi all, 
 When turn on the web protection, client's antivirus software always prompt the warning to confirm block or not(please see the attach photo). Both staffs feel so tired to confirm because it will prompt at any website. If turn off the web protection, it will not prompt again. 
 How can I solve this problem? 
 Thank a lot!

DouglasFoster · Answer

Most likely, you have two problems: 
 
 Your configuration is too strict, and this URL is generating a block or warn page from UTM. 
 You have not distributed the UTM CA root certificate to your client devices, so the block or warn page does not have a trusted certificate chain. 
 
 For a block or warn page to display at all, UTM has to impersonate the remote server. If the user navigates to example.com, but the browser gets a reply from utm.mycompany.local, it will ignore the reply. So UTM replies as if it is example.com. 
 In http mode, this is easy because there is no way for the browser to check identity. 
 In https mode, the secure session has to be established before the reply can be sent, and the session requires proving identity with a certificate chain. So to send the page stating that example.com is being blocked, UTM uses its certificate authority to generate a certificate to prove that it has the right to claim to be example.com. This certificate is only trustworthy if you have installed the UTM CA certificate to say that your device can trust anything that UTM says. 
 Consequently, the antivirus software is doing what you asked it to do. If it was not generating the certificate warning, the browsers would do it instead.