Hello Dave,
There are quite a few comments on this topic on this forum, with various solutions and approaches dependant on the environment.
Check out the sticky 'Solving NFS issues ...'
I can share my experience with you - but it will just be one of several approaches.
First - the problem varies with the firmware version. I'm using 5.2.0
It also varies with the network file sharing protocol and NAS type. I'm using SBM/CIFS (ie Microsoft networking) on my QNAP NAS, not NFS.
I have found that recording works OK when the available volume size is 200GB, doesn't when it's 250GB. I've not explored the actual boundary. So I created a dedicated volume to apply the size limitation.
I have needed to have a network share dedicated to each camera, it doesn't seem possible in the camera configuration to specify subfolders per camera in a common share, ie /sharename/foldername
What I haven't explored yet is applying per-user size quotas. Another forum member did this successfully on a Synology NAS, saved having to create new volumes.