How to configure QTS to use MDNS

Hi, I’m a Linux user. I use my QNAP NAS with NFS for my Linux PCs and laptops and want to restrict access to NFS for these devices. The long way to do this is allocate static IP addresses and use these in the Shared Folders configuration. However, this is a hassle and what I do with my other servers is use MDNS. Does anyone know how to configure this in QTS?

I see that MDNS works with QTS because I can log in with ssh and use the ava-resolve command:

avahi-resolve --name example.local

I would normally configure nsswitch.conf to include the multicast lookup in the resolution chain:

hosts: files mdns4_minimal [NOTFOUND=return] dns

But QTS overwrites nsswitch.conf (and hosts) on restart. So how should this be done?