Images not shown in gmail - Passbolt on private IP

Hello,

My passbolt installation is in private network in the AWS, only accessible via VPN. This is of course for the security reasons.

But when mails are sent and any notification, there are no images being displayed.
My question is, is it possible for the images to be shown in the gmail client at all, because installation is behind “closed doors”.
Thank you.

Uros