I have two LAMP stacks running a single Wordpress instance under a load balancer. Each server runs Varnish, and I need Varnish to purge the front page (and some others) with each post update, etc. So I added the two IP addresses to the 'Varnish servers' field under W3 Total Cache's General Settings -> Reverse Proxy section.
Now when I update a blog post, PURGE requests are sent only to whichever server comes first in that list. If I reverse the two servers, the PURGEs go to the server which is now on top.
I have tried as delimiters for this list newlines, commas, semicolons, and spaces. Any characters other than newlines and spaces cause W3 Total Cache to not send PURGEs to *any* Varnish instances.
In the future, I'll potentially be adding more Varnish servers, so I definitely need this working. Is this a bug, or am I doing something wrong?