Rebooting Rasp Pi/Hassio, https://hassio.local:8123 & https://[ip address]:8123 "work" (get a private connection browser error), DuckDNS URL no longer works getting "Unable to Connect"

Hi Folks-

I did a simple reboot of my modem, but now find I can no longer log into the Hassio front end consistently via my DuckDNS url via the web. Doing a full reboot, I understand that the actual IP address changes. I updated this in DuckDNS, and all works temporarily. The moment I restart Hassio by making a change, for some reason in DuckDNS the IP address reverts to what it was previously and I have to repeat the process again.

What piece am I missing? The moment I update the IP address in DuckDNS everything works great: I’m able to navigate via my duckdns URL, but again (for example) I’ll make a change in my Configuration.yaml file, reboot, and I’m back to doing the same thing in DuckDNS. Never had to do this before prior to my rebooting of the modem. What am I missing?

Edit: Stupid me. When my modem was reset, it reverted back to it’s former state as a combo modem/wifi router. Not sure why just rebooting resets this! Set my modem back to bridge mode which solved the IP address issue.