@roquito,
Glad you showed Hugo the error message. We would not have figured-out that you were doing your HTTP commands within the device. As Hugo mentioned, the “agent” is who communicates with the outside world. Your device (the physical imp) only communicates with the agent.
You want the imp to access IFTTT, so your imp sends its data to the agent (who is always waiting for it), and the agent does the GET or POST to IFTTT.
Your agent is also given its own URL. If you wish to affect something on the imp hardware, you POST to the agent, and the agent communicates with the imp. I like to experiment with the IFTTT webhooks. For example, IFTTT has an app to trigger a remote URL when my cell phone gets within a certain distance of a location (my house in this case). That remote URL is my imp agent. The agent then sends data to the physical imp (device) that turns on an output pin. That turns-on outside lights on my house.
Think of the agent as the “middle man”.