I had a similar problem with my HP EX495, I found suspend setting unreliable - if you change all the settings to hibernate rather than suspend this works as described.
If you go to the general settings in lights out
click the cogwheel near the WHS logo in the main window, scroll down to the lights out app
go to the action tab and change standard action to hibernate
You can try P2V'ing your existing physical server and export it as an OVA "appliance" file from either VirtualBox or VMWare Workstation, which you can then import into QNAP's Virtualization Station "from PC"
You wouldn't be using ISOs in this case would be if you were installing it from scratch within QNAP's VM Station. Just make sure your chassis has enough physical RAM to support the amount of physical RAM your existing WHS2011 box is using. There's a good chance the QNAP won't be fully compatible with the OVA/OVF file you export from VirtualBox or VMWare, but that would be how I'd go about trying to do what you want to do.
I ran WHS 2011 as a VM within 2012 Essentials for about 7 months before I ran across an issue with using raw disk passthru and writing more than 2.2TBs of data to a drive within VirtualBox --- any "gotchas" or surprises depend on which environment you're virtually running it on.
If your using a QNAP NAS go to QNAP.COM, Support, Tutorials & FAQ, Tutorials, Virtualization Station. This details how to do it. Basically you copy the installation disc as an ISO file and then create the VM pointing to the ISO. Select the console and complete the usual Windows install procedure. If I remember correctly there is no specific option for WHS2011 VM so just use the 2008 Server R2 VM option.