Using ipMonitor for SSL certificate days until expiration monitoring.

This monitor functions perfectly on 12 of 16 sites.  On 3 of the 4 that are failing, I receive an "Unexpected disconnection from the remote device" error when enabling the monitor.  On the 4th, I receive a "The remote device could not find the requested file; expire in 224 days; http: 404" error when enabling the monitor.  In all cases, I'm using the HTTPS monitor with the website url for the IP Address/Domain Name which resolves to the external, public IP address.  I am not searching for specific text string and have "/" for the URL.  I can reach the websites from the ipMonitor server for the successful and unsuccessful monitors.  This is all on version 11.1.1 build 980 of ipMonitor.  Any suggestions on remediation would be appreciated.