This is needed if you want to make services available from the Internet from a changing (dynamic) IP (widely used for private intrnet connections). This may also be needed to validate SSL-ACME-Challenges used by letsencrypt.
Please look first at the playbooks downloaded and run by the install.sh to understand whats going on and then decide if it is fine for you to run on your system.
You also should test this on an non-productive Test-System to fit your needs.
- you can manually or check update with ```sudo dedyn.sh```
- you may need to create some Portforwardings or IPv6-forwardings in yout router to be able to access your device from the Internet. Often used ports are 80 and 443 for http and https for example.