Distributed Erlang has a security model that is unofficially described as “this space intentionally left blank.” Do not run it over a WAN or other public network layer, because the shared cookie is not a form of privacy, encryption, or meaningful authentication. It has about the authority of a code word to a kid’s tree house.

On economy hosting like OVH/Kimsufi/Hetzner that means opting for the private network options, which may come with a shocking premium or other caveats that put the pin in the too-good-to-be-true pricing.

I really, really recommend you do your own homework here after you receive whatever feedback this thread includes, including about my own points. It’s very hard to mitigate security risks without a solid understanding of the threats involved.

Don’t know about others but Hetzner does provide free private networking between your resources.

You can also run erlang distribution over tls with two-way encryption (iirc) which will be secure, at which point the only thing you have to worry about is latency.