If you have an SSL certificate on your server, the External Images plugin will proxy any http (non-https) images through your server to avoid breaking the SSL padlock.
If you are finding that this is not working for you, you need to edit your php.ini settings to allow External Images to fetch remote images.
From your front-end shop page, or front-end product page, right click the broken ‘image’ and choose ‘Inspect Element’ (with Chrome browser, other browsers vary).
You will see the <img> tag and you will see a src=”https://…..” link. Right click the link inside the src attribute and choose ‘Open in new tab’ from the context menu.
You will either see the image, or you will see this message:
We couldn’t load the image file type. Either this is an invalid image, or your php.ini settings on your server needs the allow_url_fopen = On setting (instead of Off)
Fix by editing your php.ini file
Open your php.ini file with whichever editor you use and find the following line:
allow_url_fopen = Off
and change it to this:
allow_url_fopen = On
Now the External Images plugin will be able to fetch the remote images and proxy them successfully.