Why not use a different DDNS service? There are plenty out there. :) I think this may solve your issue. I’ve been using freemyip.com’'s for a while and have had no problem in the past issusing LetsEncrypt SSL’s. At the moment, I’m on Cloudflare tunnels so it’s automatic with them, which I know is a huge trust issue for a lot of people, but I don’t mind it for my stuff. But I do like to have my DDNS as a backup service from time to time.