Important note about SSL VPN compatibility for 20.0 MR1 with EoL SFOS versions and UTM9 OS. Learn more in the release notes.

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Sophos XG : NET::ERR_CERT_COMMON_NAME_INVALID

HI all, 

Hoping you can help. 

Recently an external website we access has been updated and hosted elsewhere. Following the move we now get the following error but only when connecting via the VPN (Remote access).  We can browse to the site without issue without using the VPN connection. Its a HTTPS site.

Error is : NET::ERR_CERT_COMMON_NAME_INVALID 

Now in my limited knowledge and with some basic searching this seems to point to some sort of issue with the Cert for the site but would that then not be an issue in general not just for when we connect the VPN?

I have attempted to add the website as an exception just for testing but the issue remains. 

Any suggestions on how to resolve this or things to check in the firewall would be gratefully received. 

Thanks.



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  • Hi  

    After all the steps mentioned above I'm still experiencing this issue.

    For me it's exactly as described in the KBA Article linked by  . The fix sets the values to the ones that were already configured:

    I'm trying to access https://google.com however I'm getting a "NET::ERR_CERT_COMMON_NAME_INVALID" error with the following cert. Notably, https://www.google.de or any other regional variants work fine.

    Unfortunately I am not able to reissue this certificate as suggested for obvious reasons.

    My Web proxy configuration is identical to  .

    Any further suggestions would be appreciated.

  • Further investigation showed an outdated DHCP Relay config.
    Disabling ipv6 and correcting old DNS server entries on the domain controller as well as a reboot resolved the issue thereafter.

    Presumably a gateway/router reboot without booting the domain controller caused a conflict.