Takis,
Thank you for your response and information. Looks like I installed wordpress in a subdirectory. So, I’ve changed the adaptive-images-actions.php file and removed the $request_uri_base. part.
Refreshed everything but no changes visible when going to the website from mobile or smaller screen devices.
According to my hosting company they are using Nginx only as a caching server. Apache is still the main server.
Riaan