Our environment is using pulse on both Windows and Linux, we recently upgraded our appliance to a virtualized appliance.
Windows machines continue to connect without any issue but our Linux machines open, prompt for credentials and then the window closes and it just has the lists of connections again and it stays disconnected. I have already tested by updating the client to 5.3r2 and the same behavior exists.
Is the virtual appliance using a self-signed certificate? I've seen similar symptoms in the past due to the client was not able to trust the device certificate. Here are some details about the issue and resolutions steps: