Timeout for SNS

Question

I've been using sendy.co (self-hosted) to send emails via Amazon SNS / SES for over a year. It was less then around 350 emails / week.
Today I've noticed that something is not working properly, and I'm getting timeouts.

It's endpoint: https://sns.us-east-1.amazonaws.com/?Action=ListSubscriptions
Error communicating with Amazon SNS API.
Failed to connect to sns.us-east-1.amazonaws.com port 443: Connection timed out

So I created a simple PHP script with curl to 
1. https://sns.us-east-1.amazonaws.com/?Action=ListSubscriptions and returns Failed to connect to sns.us-east-1.amazonaws.com port 443: Connection timed out
2. https://3.239.232.78/?Action=ListSubscriptions returns Failed to connect to 3.239.232.78 port 443: Connection timed out
3. https://wykop.pl/  - works fine (checking if curl can reach any other website on port 443)

This fails only when script is from from shared hosting - 86.111.241.88
It works fine when it's run from other VPS 95.217.75.29 or my local pc - 88.156.128.60

Does it mean that above IP 86.111.241.88 - is blocked on Amazon's side?
If so, how can be unblocked?

Accepted Answer

I cannot tell whether you fell under a deny list or what... but to be honest I would try to check on this points and see if something rings...

* Verify that outbound access is allowed on port 443 in your EC2 security group. SNS uses port 443 for HTTPS connections.
* Check for any network ACLs that may be blocking outbound traffic to the SNS endpoint IP range.
* Try simplifying your code and running basic SNS publish/subscribe tests to isolate where the issue may be occurring.
* Consider using alternative SNS endpoints in different regions in case the primary endpoint has availability problems.
* Review your AWS service health dashboard or service health history for any known issues on the day you encountered this problem.

Timeout for SNS

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