This MQTT library needs IPv6 support

[sgryphon]

IPv6 is now reaching over 40% according to Google statistics; https://www.google.com/intl/en/ipv6/statistics.html

Within a few years, IPv4 will be in the minority.

Some network providers have already switched to IPv6-only, e.g. Telstra mobile users in Australia, as well as many providers in India, China, and other regions. https://www.sidn.nl/en/news-and-blogs/australias-telstra-switches-mobile-users-to-ipv6-only

e.g.

PS /home/sly/Code/iot-lab> host mqtt001-purpleiot-dev.australiaeast.cloudapp.azure.com
mqtt001-purpleiot-dev.australiaeast.cloudapp.azure.com has IPv6 address 2603:1010:2:3::73