We run a Saas serving a widget which is embedded in customer websites. The service include static javascript code hosted on amazon S3 and dynamic part hosted on EC2 with Scalr (using scalr name servers).

We received some feedback from users behind corporate firewalls that they cant access our service (while they can access the sites including the widget). This does not make sense to me since the service is using normal http calls on port 80 and our URL is quite new without any reason to be banned by firewalls.

My questions are: 1. Why is the service is not accessible and what can I do about it? 2. Is it possible that one of the following is blocked by corporate firewalls: Amazon s3, the dynamic IP address provided by amazon, Scalr name servers.

Any other possible reasons, way to check them and remedies for this?

Thanks!