CURLOPT_CONNECTTIMEOUT_MS (3) - Linux Man Pages
CURLOPT_CONNECTTIMEOUT_MS: timeout for the connect phase
NAMECURLOPT_CONNECTTIMEOUT_MS - timeout for the connect phase
DESCRIPTIONPass a long. It should contain the maximum time in milliseconds that you allow the connection phase to the server to take. This only limits the connection phase, it has no impact once it has connected. Set to zero to switch to the default built-in connection timeout - 300 seconds. See also the CURLOPT_TIMEOUT_MS(3) option.
In unix-like systems, this might cause signals to be used unless CURLOPT_NOSIGNAL(3) is set.