For future readers.
I was also just thinking, this issue could be resolved by the NFS host to allow other users access as well.
With setfacl you can allow multiple users to access files/folders.
One could run the following commands on the NFS host to ensure all existing folders and files and future files can be accessed by UID 808
# as user root or run with sudo
# Apply ACLs to existing content
setfacl -R -m u:808:rwx /mnt/nfs-backup
# Apply default ACLs for future content:
setfacl -R -d -m u:808:rwx /mnt/nfs-backup
But for this to work the NFS host must use NFSv4 with idmapping configured properly.
Also, root_squash may block expected access, but your post:
services.nfs.server = {
enable = true;
exports = ''
/export/nfs-cloudron-backups <old-server-tailscale-IP>(rw,sync,no_subtree_check,no_root_squash)
/export/nfs-cloudron-backups <new-server-tailscale-IP>(rw,sync,no_subtree_check,no_root_squash)
'';
Has explicit no_root_squash as documented https://docs.cloudron.io/guides/nfs-share#exposing-a-directory
