I realise that you say you have "excelent network connectivity and modern equipment on the client side"  but this certainly sounds like a problem with either:
(1) Your web server
(2) Your internet connection
(3) Your browser

Do you see similar problems with any of our demo galleries?
https://www.juicebox.net/demos/

Does the problem happen if you try viewing your gallery in different browsers (Chrome, Edge, Firefox, Internet Explorer, Opera, Safari)?

Please post back with the URL to your gallery's web page so that I can take a look at the problem for myself and hopefully help further. Thank you.

Feature request from bjbarouch (original thread):

Feature request from bjbarouch (original thread):

Feature request from bjbarouch (original thread):

[Copied to Feature Requests thread here.]

[Copied to Feature Requests thread here.]

[Copied to Feature Requests thread here.]

Yes. This is a known issue and a bug report has already been logged with the developers.
It should be resolved in the next version (although I do not know when this will be released).

For anyone reading this thread, this problem happens only when using web mail (e.g. Gmail).
There is no problem when using an email client program such as Outlook or Thunderbird.

If you still see the Juicebox logo in the lower right corner, then the gallery is still Juicebox-Lite.
The Juicebox logo is present in all Lite galleries but not in any Pro galleries.

First of all, please try completely clearing your browser's cache before reloading your gallery's web page to see if the problem is a browser caching issue. (Your browser might be storing and using the Lite files.)

If this does not clear the problem, then please try the Upgrading to Juicebox-Pro instructions again but, this time, try deleting the Lite 'jbcore' folder from your web server first before uploading the Pro version in its place.

Please note that upgrading WP-Juicebox to Juicebox-Pro does not change the plugin's interface.
Only Lite options will have their own individual controls but all Pro options entered in the Pro Options text area will become active.

I hope this helps.

When you create a gallery with JuiceboxBuilder-Pro, the application stores the locations of the source images in the gallery's 'config.xml' file (the sourcePath attributes in the <image> tags).
As long as you do not relocate your source images, JuiceboxBuilder-Pro will use the un-watermarked source images (rather than the already watermarked gallery images) if a new watermark is to be applied to the images (so gallery images will not be watermarked twice).

If the source images are no longer available in their original locations, then JuiceboxBuilder-Pro will have no option but to use the already watermarked gallery images and will watermark them again.
In this case, the best course of action would be to copy the gallery images to a safe location whilst the gallery is being saved and then move them back into the 'images' folder afterwards (overwriting the double-watermarked images).
The image filenames will be the same so there will be no need to modify any paths in any files.

I hope this helps.

There are many ways that you can structure your web site and Juicebox galleries.
Here are a few tips which might help.

Using the regular embedding code noted here (and presented on the 'Publish' tab of JuiceboxBuilder-Pro), the contents of the gallery folder (not the gallery folder itself) should be uploaded to the same directory as the web page containing the gallery's embedding code.

If you move of rename the gallery's configuration file (default name 'config.xml'), then you can point towards it using a configUrl entry within the gallery's embedding code, for example:

<!--START JUICEBOX EMBED-->
<script src="jbcore/juicebox.js"></script>
<script>
    new juicebox({
        configUrl: "folder_1/folder_2/configuration_file.xml",
        containerId: "juicebox-container",
        galleryWidth: "100%",
        galleryHeight: "100%",
        backgroundColor: "#222222"
    });
</script>
<div id="juicebox-container"></div>
<!--END JUICEBOX EMBED-->

No matter whether of not you use a custom configUrl, all relative paths within the gallery's configuration file ( imageURLs, thumbURLs and linkURLs) will be relative to the web page containing the gallery's embedding code.

Short descriptions of the configUrl and baseUrl embed options can be found here.

Alternatively, you could upload a complete gallery folder to anywhere on your web server and point towards it using a baseUrl entry within the gallery's embedding code, for example:

<!--START JUICEBOX EMBED-->
<script src="folder_1/folder_2/gallery_folder/jbcore/juicebox.js"></script>
<script>
    new juicebox({
        baseUrl: "folder_1/folder_2/gallery_folder/",
        containerId: "juicebox-container",
        galleryWidth: "100%",
        galleryHeight: "100%",
        backgroundColor: "#222222"
    });
</script>
<div id="juicebox-container"></div>
<!--END JUICEBOX EMBED-->

The baseUrl method of embedding is documented here.
When using the baseUrl method of embedding, all relative paths within the configuration file (imageURLs, thumbURLs and linkURLs) will be relative to the baseUrl.

Additionally, you can upload your gallery's 'jbcore' folder to anywhere you like on your web server. In fact, multiple galleries can even share a single 'jbcore' folder. Please see here for details.
All you need to do is make sure that you point towards the 'juicebox.js' file within the 'jbcore' folder within the <script> tag, for example:

<!--START JUICEBOX EMBED-->
<script src="folder_1/folder_2/jbcore/juicebox.js"></script>
<script>
    new juicebox({
        containerId: "juicebox-container",
        galleryWidth: "100%",
        galleryHeight: "100%",
        backgroundColor: "#222222"
    });
</script>
<div id="juicebox-container"></div>
<!--END JUICEBOX EMBED-->

The location of the 'jbcore' folder is completely independent of the configUrl and baseUrl options (which still work as noted above).

if you use any of the suggestions above, then you will not need to modify any of the paths inside the gallery's configuration file.
However, if you want to store your images elsewhere on your web server (not inside the 'images' and 'thumbs' folders within the gallery folder), then you will need to manually modify the paths (the imageURLs, thumbURLs and linkURLs) inside the gallery's configuration file (by opening the file in a plain text editor) bearing in mind that if you use a baseUrl, then relative paths will be relative to the baseUrl.

I hope this helps.