We need our server to receive notifications about changes in subscription statuses. To achieve this we followed the instructions from https://help.apple.com/itunes-connect/developer/#/dev0067a330b.
Our server supports App Transport Security (ATS) protocol. It was tested with this service https://apptransport.info/. So all requirements seem to be fulfilled.
We entered the target URL into the “Subscription Status URL” field. But we haven’t received a request (GET, POST, PUT) to the specified address after starting and expiring subscriptions in our sandbox.
Is there any way to troubleshoot this kind of problem?
Apple support helped us to find out the reason of our problem.
We are receiving a 403 response for server notifications that are being sent by the App Store.
So we should try it with curl before asking this question. Now we receive updates correctly.