Firefox won't connect to some pages on site


I have recently moved servers because of a variety of issues and the site is now running very well on Chrome and Safari but I am having problems with Firefox. It won't connect to some sections of the site (or sometimes it does if you leave it for several minutes). I think it is only the Woocommerce product category pages that have a problem. They did work before and they still do work in the other 2 browsers.

The url is:

and the page from where you can link to the product categories is here:

Can anyone offer any suggestions please? I'm really stumped.

many thanks