How do we get rid of "Exception: Network is down" aka ENETDOWN error?

We are using a rails API project which interacts with a DotNet WebApi 2 project.

When I consume APIs in the DotNet API project using postman, I'm getting the response normally. But When I try to consume the same API inside the rails API project, I'm getting ENETDOWN error.

We're only facing this issue when calling APIs in Dotnet Project (Which is in another server) from the local Rails API project.

We're sure that the issue is in the Rails API project. But we couldn't figure that out. Reason to believe this is We are getting data from the DotNet project using postman.

It would be great If anybody has any idea what happens here.