A Dynamic Domain Name System, often called Dynamic DNS or just DDNS, allows you use a static host name with a dynamic IP address.
The TP-Link modems that NCF sold between 2011-2017 support DDNS and it is easy to configure though the modem's graphic user interface.
For complete information on how to set up DDNS see:
- TP-Link 9970 User Guide (page 100)
- TP-Link 8951 User Guide (page 80)
- TP-Link 8816 User Guide (page 55)