The media could not be loaded, either because the server or network failed or because the format is not supported

Hi, relatively new to video hive and using after effects, but I’m find ing my way around. However, just suddenly all the after effects preview videos has started showing this notice ’ The media could not be loaded, either because the server or network failed or because the format is not supported ’ and I can’t watch the preview.

I can watch if I download the preview, but I don’t want to have to do that each time.

I’m using windows 10, and have changed nothing on the computer, it was fine, - this has just started happening.

any advice?