Connections to remote MQTT servers are not supported for security reasons.
Connections will only be established to MQTT servers in the local LAN. I.e. either the
hostname has to resolve to a local IP or a local IP is given as hostname (10.0.0.0 -
10.255.255.255, 172.16.0.0 - 172.31.255.255, 192.168.0.0 - 192.168.255.255).
Source: MQTT API Specification