Cert Error for Web Block Page

Question

For BYOD we are not planning on forcing users to download the Sophos Cert, we are not performing any HTTPS packet inspection on our wireless networks so users should just be able to connect and browse. This appears to be working without issues apart from one thing. 
 We are still blocking some categories such as gambling, pornography etc. These sites are being blocked successfully, however instead of displaying the block page, it just comes up a certificate error. Is thee any way of getting the block page to show without having the Sophos Cert installed on the end user devices? 
 This is not a problem for our corporate network since we have the Sophos Cert pushed out via GPO, so everything displays correctly.

FormerMember · Accepted Answer

Hi David Ashcroft, 
 If you are blocking a category such as Gambling and a user goes to https://www.pokerstars.com/ then you want that web request to be blocked. The web proxy sees that the client is trying to go somewhere they should not and wants to display a block page. In order to do so, they need to do man-in-the-middle decryption so that it can insert a block page that pretends to be www.pokerstars.com. 
 Check out this KBA for more detail : HTTPS Decrypt and Scan FAQ . 
 Thanks,

FormerMember · Answer

Hi David Ashcroft, 
 Unfortunately, there is no way around it and display the block page as HTTP instead of HTTPS. 
 Thanks,

Cert Error for Web Block Page

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