Unable to Connect SAP Analytics Cloud to an External HTTPS REST API

[#1]

Requirement

We have an external REST API exposed over HTTPS. The API requires authentication, and I want to consume this API from SAP Analytics Cloud. I have created an HTTP API connection in SAC and provided the required authentication details. However, I am unable to successfully connect to the API. 

SAC configuration

• Connection Type: HTTP API
• Protocol: HTTPS
• Authentication: Basic Authentication
• API: External HTTPS REST API
• SAC Environment: SAP Analytics Cloud Trial

I have verified that the API is working independently outside SAC.

I have also tested the API using an external REST client, and the API responds successfully. However, when I try to use the same API from SAC, the connection/request fails.

I also tried using the API from a SAC Multi Action through an external API step, but the request was unsuccessful. In one of the tests, I received an HTTP 405 – Method Not Allowed error.

What I would like to understand

1. Can an external HTTPS REST API with Basic Authentication be consumed directly from SAP Analytics Cloud?
2. Are there any specific configuration requirements for creating an HTTP API connection in SAC?
3. Does SAC require the external API to support a particular HTTP method such as GET or POST?
4. If the API accepts POST requests, how should the HTTP method and request payload be configured in SAC?
5. Are there any restrictions or limitations when using HTTP API connections or external API steps in an SAC Trial tenant?
6. Could the issue be related to authentication, SSL/TLS certificates, API gateway configuration, or SAC connectivity restrictions?

I would appreciate any guidance on the correct configuration and troubleshooting approach.

Thank you.