Cannot mount NFS Share inside Debian 11 LXC with installed Proxmox Backup Server package

[EpicLPer]

Heya!

I'm currently setting up a test-environment to play around with Proxmox VE and the Backup Server to then set it up in a proper homelab environment.
I've set up PBS inside a privileged LXC Debian 11 container via the "proxmox-backup" package, and tried mounting a NFS drive inside of it. However I'm always getting a "Permission Denied" error back from, apparently, the NFS Server. However I've tried it on various other Linux machines, and it works perfectly there, all in the same subnet which I've given access to in the NFS permissions for this Share.

root@PBS-Test:/mnt/SynologyNFSMount# mount -vvvv XXX.xxx:/volume1/ProxmoxNFS/PBS_Backups /mnt/SynologyNFSMount/
mount.nfs: timeout set for Mon Sep 12 12:07:44 2022
mount.nfs: trying text-based options 'vers=4.2,addr=10.0.0.12,clientaddr=10.0.0.122'
mount.nfs: mount(2): Permission denied
mount.nfs: trying text-based options 'vers=4.2,addr=10.0.0.11,clientaddr=10.0.0.122'
mount.nfs: mount(2): Permission denied
mount.nfs: access denied by server while mounting XXX.xxx:/volume1/ProxmoxNFS/PBS_Backups

Is there anything I'm missing here? I've tried other protocol versions already, also tried adding a config line to the LXC container that apparently "should have helped" but it didn't. The line was "lxc.apparmor.profile: lxc-container-default-cgns".

I'm new to Proxmox, so thanks already for your help

 

[EpicLPer]

And... suddenly, after writing this, it... works??
The only thing I tried right now, out of desperation, was to disable the Firewall checkmark at the network settings, and suddenly it mounted... and then after that worked decided to check the Firewall mark again, and it still worked...

I have no idea what I just did to make it work, but apparently it... worked.

Gotta love the IT world sometimes