Thumbnails not showing in admin or on frontend

I’ve recently had to move one of our higher traffic sites over to a Rackspace multiple cloud server solution, with Varnish caching active.

The problem is that, in moving the site across from the old VPS, none of the thumbnails for the files presently held by WP-Filebase are showing any longer (either in the admin or on the frontend). Permissions are set to 775/664 and ownership assigned to apache. I can upload a new thumbnail and see it appear in the relevant folder, but never actually see it.

I’m presuming this is an issue with Varnish, so has anyone out there experienced anything similar?

Perhaps there is a way to include rules such as in the following article:

https://docs.woothemes.com/document/configuring-caching-plugins/

Or some rules I could include in the appropriate .vcl file?

Any help would be much appreciated ??

https://www.ads-software.com/plugins/wp-filebase/