Dynamic DNS – Dynu.com

Chose dybu.com

https://www.dynu.com/
https://www.youtube.com/watch?v=wCJjiHp0d0w use that
https://www.youtube.com/watch?v=ZKEGP_qBmxg and this to fill the gaps.
https://www.dynu.com/DynamicDNS/IPUpdateClient/RaspberryPi-Dynamic-DNS specific to pi

Unable to get the router port forwarding to work.