First you install the CIFS utils.
sudo apt install cifs-utils
utf8 seems to not be available in ARM Ubuntu Server 22.04 systems, you can check that.
ls /lib/modules/$(uname -r)/kernel/fs/nls/
To download the rest of the character sets.
sudo apt install linux-modules-extra-$(uname -r)
To mount SMB3 with seal (encryption) make sure you create a subuser in your storagebox and assign SMB, you can then create the file /etc/cifs-credentials.txt with the following text.
username=u000000-sub1
password=
Make sure you put the permissions on 0600 by running the following command:
sudo chmod 0600 /etc/cifs-credentials.txt
Then try to mount it with sudo, with the following command:
sudo mount.smb3 -o seal,credentials=/etc/cifs-credentials.txt //u000000-sub1.your-storagebox.de/u000000-sub1 /mnt/hetznerbox
If you receive no error messages, you go to /mnt/hetznerbox and create a file or folder, here we create a file:
touch /mnt/hetznerbox/test
Try to unmount it after creating the file, and see if the file is no longer there:
sudo unmount /mnt/hetznerbox
And check for the file:
ls /mnt/hetznerbox
If the file is no longer there, and after running the mount again, and ls in the folder and the file has reappeared, you can confirm that your mount is working properly.
You can also make sure by activating SFTP in your Storage Box with the same credentials so you can verify with WinSCP or Nautilus
After all that is done, you can edit the /etc/fstab file so you can make sure it mounts on boot.
/etc/fstab
//u000000-sub1.your-storagebox.de/u000000-sub1 /mnt/containers cifs vers=3.1.1,seal,iocharset=utf8,rw,credentials=/etc/cifs-credentials.txt,uid=1001,gid=1001,file_mode=0660,dir_mode=0770 0 0