Freshservice intergration with on-prem Endpoint Central

, none of the related Topics are remotely close to my question,I am setting up Freshservice integration with on-prem Endpoint Central. When I test the connection, I only get errors. I added the IPs that Freshservice's “Support” provided, and it still fails. FYI none of the related Topics are remotely close to my question so I am just picking one.