Nginx proxy manager / DuckDNS - Hmmm… can't reach this page

I had everything working for months, but for some reason my certificates didn’t get renewed.
Now I tried setting up a new proxy, but at the step (in the example gif) that the created link “” is clicked, I don’t get the log in screen but a screen with Hmmm… can’t reach this page
When I directly go tho I get the log in screen.

Where to find the solution !??