There have been some reports about issues with the Updater not updating anymore. Please try the latest beta version and switch to another IP Check provider instead of the previous default dnsomatic.com. For some reason they are rate-limiting the number of requests to their service. The new IP Check provider selection allows you to choose another provider in such cases. You can test the functionality with the new "Test" panel.
First of all, i wish you a happy/healthy new year!
I would like to know, what's the plan, when will you release 2.0? If i understand fine, the "custom provider support" is mean, if i have own dyndns solution with dyndns2 protocol, Marcs Updater client is works with my own server?