I tried using DuckDNS for a while for DDNS, but noticed it seemed to have frequent periods of a few minutes each when it just wouldn’t resolve. Also was unable to get a matrix/synapse setup working behind it. It’s handy as a free service and nice if you just need basic DDNS, but it’s not the most reliable for hosting stuff from my experience.

I eventually settled on buying my own domain. Was much cheaper and easier to figure out DNS management than I was expecting, and my hosted services run so smoothly now.