Hi dr,
Not sure you will find many geniuses here, but here's one familiar with networking concepts. Unfortunately I am not familiar with sniproxy, and too busy to look it up now. 🙂
Access Server does not provide DNS service. If you want DNS service through OpenVPN Access Server you must install and run your own DNS resolver software, or use an external resolver such as Google or Cloudflare.
You might be interested in the
OpenVPN Cloud service, which does provide DNS services and filtering features.
regards, rob0