specific images for Mobile

Hi,
in the module settings there is an option "Use specific images for Mobile" - I change it to 'yes' but apart from the fact that in such a situation no image loads on mobile nothing else happens

The main slider on the desktop is 1920 px, on mobile I have to have it much smaller because the pagespeed results are poor.

What else do I have to set in the module to have a different image on mobile?

Regards, Gregory

Hi
Please give me the url of the page, with the option activated so that I can check
CEd

The module option is confirmed (attachment).
Nothing loads in mobile view.

cedrowa.eu/2lonorwid/

the problem is that the images do not exist
example
images/slideshowck/640/slider-01-wrzesien.webp

check in the advanced options of the module that "create thumbs automtically" is enabled. ELse you must create the images yourself in the folder

Ok, I have it now - thank you for your answer.

I didn't find any info about adding photos to the '640' folder - my mistake.

Finally, a question about the quality of the photos, they look different than they should, is their quality reduced by some additional settings? Do I have any influence on this?

the images are 640x360 px
but the container of the slideshow has a height of 100vh, for example on my screen it renders 920px height
imagine now that your image is about 2.5x bigger than its original size ... of course it does not render correctly

and the slideshow can not do anything here, if you want you can modify your images in the resolution folder