This is a question that has come up quite often and I have blogged about this for several different products in the past. What Firewall rules do I need to create to install and use the Pure Storage Plugin for the vSphere Web Client? Luckily this is fairly simple. For instructions on using and installing the Web Client plugin check out these posts here and here.
When you go to install the plugin from the array GUI and you see the following error it could very well be a network error: