Suneido is still actively maintained (check the version control) although I have been very lazy about putting out new releases 🙁
I am the primary developer on the C++ and Java implementations, but there are more people working on stdlib stuff.
My commercial company (Axon Development) uses Suneido to develop it’s software. We are approaching a million lines of Suneido code in our application, with hundreds of customers who have, in total, thousands of users. So Suneido is not going away any time soon.
Suneido is designed for local area networks and does not run well over a wide area network (such as the internet), more because of latency, not bandwidth.
To support remote users for our clients we use remote desktop services.
I hope that answers your questions.