We currently do not have a set IP-range. A Data Connector request origin can be verified by using Signature Secrets. You can read more about Signature Secrets on the Advanced Configurations page.
Verify that your Data Connector is configured with the correct Endpoint URL.
Check your endpoint logs for tracebacks that explain the source of the error.
A Data Connector can be automatically disabled if only non-200 responses have been returned for a long time. You can read more about this on the Advanced Configurations page.
Data Connectors are best used in backend integrations where a reliable and secure stream of events is desired, like forwarding events to external long-term storage. It comes with quality-of-life features such as an at-least-once Guarantee, low latency, and automatic scaling.
On the other hand, the REST API Events Stream provides a service aimed more at front-end applications and trades some quality-of-life features for flexibility. Granted the right permissions are given, a stream can be set up anywhere but does not come with the same at-least-once guarantee as a Data Connector.