Instagram Subscription - Unable to reach callback URL - ONGOING

Question

This problem has been published many times, but I have not yet found a solution. I contacted Instagram developer support, but after a week I was still out of luck, or the answer shaped them so that someone could help me. My app has been approved by Instagram for basic permissions.

Running the POST form for https://api.instagram.com/v1/subscriptions/ with all the relevant data (callback_url, object = user, aspect = media, verify_token, client_secret, client_id) to create a subscription for Instagram user subscribers gives an error: APISubscriptionError - unable to get callback URL

• The callback URL that I use is registered on it to register all requests that work when accessed directly through the browser. Using magazines, I see that Instagram has not even reached my callback URL.
• The callback URL is publicly available over the Internet, and the domain is used in production.
• The callback URL implements the GET and POST methods (even PUT just in case).
• Worked a few weeks ago using the UAT URL.
• The callback url still returns “Unable to reach the callback url” using http or https.
• I changed the IPs, used a VPN and ran a post script in different places.
• Tried different parts, for example, domain.com/instagram/subscriptions or domain.com/instagramsubscriptions -Tried another subdomain and a different URL.
• Removed all subscriptions using DELETE request

Any help or suggestions would be greatly appreciated.