A note about container technology is that at least with LXC or LXD, containers are not allowed to mount network folders. Instead, you need to mount via the host and expose the folder to the container.
NFS Server Configuration
Separate article will be written on setting up.
This is the key article to understand how to do it. It's not user based but ip range based on the Synology system,
NFS Client
Install nfs client software,
sudo apt-get install nfs-common
After ensuring IP was setup properly it was just a matter of,
cd ~ mkdir -p mnt/guest.public # forget if I also need to make the subdirectory sudo mount -t nfs 192.168.0.5:/volume1/guest.public ./mnt/guest.public/
Setup Automatic Mounting on Startup
...
References
Benchmark on best Mounting Protocol for Ubuntu
Speed Comparison - https://ferhatakgun.com/network-share-performance-differences-between-nfs-smb/