I'm seriously setting out to do hosting using Virtualmin Pro, and it's scary. I see that there are a LOT of tiny things in Virtualmin that don't work. No doubt many of these shortcomings are the fault of the underlying operating system. But casting blame achieves nothing; what's important is how to make it work.
I suspect the Virtualmin Pro developers have stretched themselves too thin, and are not able to fully support everything they want to offer: All the various OS environments, all the various subsystems for mail, web, and databases, and all the other miscellaneous things like installing scripts, installing a Let's Encrypt certificate and so on.
(This could be a vicious cycle. i am not sure. If many things don't work, then they have fewer paying customers, and fewer resources to make things work, and so on.)
So here's my question: Which is the ONE operating system that they think they can BEST support for the next 2–3 years, with the FEWEST possible problems and the best possible reliability?