"Attempt to connect to endpoint failed"

[manicslothpdx]

I have set up a Kinobi server partially successfully. When I click the "test" button in Jamf, "SERVER STATUS" is green but "SOFTWARE ENDPOINT VALIDATION" fails with the message ""Attempt to connect to endpoint failed." I am running both Jamf and Kinobi on identical but separate CentOS 7 VM's on AWS. Google doesn't seem to be much help. And, if I try to add a patch title in Jamf, the error message in the Patch Management section is "A connection error occurred while attempting to download software titles from this source."