Resolution on each possible cause as below1) Network Firewall Blocking
Resolution: Verify your configured port used on HCP and set it whitelist.
2) DNS resolvation failure
Resolution: Verify the FQDN are able to be resolve on the Sharepoint Server else make amendment and make sure it is resolved to the correct IP address of HCP
3) Using the wrong endpoint connection (each namespace has own DNS)
Resolution: Navigate to HCP name space and search for the correct configured Name space and IP address used ( can get assistance from HCP vendor)
4) using the wrong protocols
Resolution: confirming Which protocol you use,
- If HTTP then value to be configured on endpoint connection "Use SSL= No".
- If HTTPs then value to be configured on endpoint connection "Use SSL= Yes".
Sample screenshot
5) Entering the wrong format of value in Host field. eg wrong value format : https://<fqdn>, http://<fqdn>,http://<Ipaddress>
Resolution: No http:// or https:// is involve , when entering the Host field , only use IPaddress or fqdn , eg. x.x.x.x or namespace.hcp.fqdn, depending on the requirement
6) Namespace value is not entered in Advance Adapter Settings for specific NameSpace.
Resolution: Enter the value of the name space created in HCP platform, can get assistance from HCP Vendor