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 This software lets you turn your [Qubes OS](https://www.qubes-os.org/) machine into a network server, enjoying all the benefits of Qubes OS (isolation, secure inter-VM process communication, ease of use) with none of the drawbacks of setting up your own Xen server.
 
+**Note**: this software only supports release 3 of Qubes OS.  For Qubes OS release 4.0 support,
+please see `r4.0` branch.  Release 4.1 is on the works.
+
 ##Why?
 
 Qubes OS is a magnificent operating system, but there are so many use cases that its networking model cannot crack: