Hello Zd,

sounds like VPN is the way to go, it is built in into all modern
Operating systems
and even cheap household ADSL-routers have VPN capabilities built in

> This is a no go as my clients won't be spending thousands of
> dollars on buying a server + the licenses...

> The app I'm selling is very cheap, and I need a very cost-effective solution...

Happy New Year!

--
Mit freundlichen Grüssen
Hannes Streicher mailto:HStreicher@...