Hi, can you guys help us to solve this issue?

We are currently setting up our development meta app to webhook. But we had issue when we want to verify our webhook url callback with verify token with it, it said that:

Callback verification failed with the following errors: curl_errno = 35; curl_error = OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to (our dns webhook:443); HTTP Status Code = 200; HTTP Message = Connection established

We already prepare our url webhook with logic to return hub challenge as documented in https://developers.facebook.com/docs/graph-api/webhooks/getting-started/#create-endpoint. We also had our WAF, Load Balancer, and our app server injected with cert SSL properly.

For additional information, we can access our webhook url on postman or web browser and it can return the hub challenge that we set on url query params.

Is there any SSL Certificate from META that we have to inject to our environment? or the steps that we do to inject SSL Certificate are incorrect? Do you guys have same issue like us? please let me know how to solve this issue.

Thank you