it is basically very simple to start mumble (murmur) on your qnap nas. (atom cpu)
ssh into your qnap then download murmur from sourceforge:
tar fxv murmur-static_x86-1.2.3.tar
-> make shure to set password + uncommend
levae the last thing blank if you want a public server.
then make also shure that the mumble typical port is open: 64738
then simply start it:
and exit from the shell. (it will keep running even without nohup)