What is The cURL (28) Error, Couldn't connect to server?

The cURL (28) indicates a proxy connection error. The full error traceback looks like the following:

curl: (28) Failed to connect to XXXX port XXXX after 21057 ms: Couldn't connect to server

This error arises when the cURL request can't connect to the proxy server, either because the server isn't responding or the proxy details are invalid. To solve the cURL (28) error, double-check your proxy IP and port or use another proxy, as it can be down or unresponsive.

For further details on proxies, including their types and best practices when choosing a proxy, refer to our introduction guide.