Background
I have a NAS drive (QNAP) that supports both NFS and Samba.
The NAS has 2 share folders of interest to this story. 1) is called Public and is completely open for full access. 2) is called Multimedia and I have changed this to also be full access to anyone.
I have "Raspberry PI 3 model B"that I have been using for several years. It is running 9.01 of LibreElec and use NFS to connect for movies and TV library on the NAS.
I found my older Raspberry PI 2 model B+ and installed new SD card with LibreElec 9.0.2 (and again with matching 9.0.1).
I have made a backup from this working PI 3 system and restored the backup onto the PI 2. (I decided to change the hostname on the PI 3 before the restored on the Pi 2 to prevent a clash).
The restore worked fine and all settings look good.
Problem
The NFS mount points are not working on the PI 2 with restored settings from the PI 3. It says the network is not connected.
If i browse to set up a new network path it allows be to browse the pubic folder on the NAS driver fine but not for the Multimedia. I.e. it shows the top level folders but does not let me navigate into the Multimedia folder where as I can navigate into the public folder.
Both folder still work find on the PI 3 and I can navigate into any of the folders.
NFS does not require credentials and I have double checked the permissions on the NAS.
Work around
I have now had to change the PI 2 to use Samba instead of NFS and it is working now.
Unexplained
Why would it work differently for two systems that are almost alike?
I can't imagine that a difference between PI 2 and PI 3 would cause this difference as the drivers must be the same.
The only other difference I can think is the PI 2 is on a different managed Cisco switch (witch is connected the main router/switch) and where as the Pi3 shares the same router/switch as the NAS.
Question
How would you approach the triage and diagnosis for this?
It there something I have overlooked with NFS?
or
Is it time to fire up WireShark and snoop the network?
or
Is there full logging that can be turned on in LibreElec that may show what is happening with the NFS?
(If logging is possible please would you link the instructions).