After upgrading to Armbian 26.2, I noticed that if I mounted a network drive (samba, cifs) and even accessed it, and then tried to unmount it (sudo umount -t cifs ...), the system would freeze. Upgrading from Debian 12 (bookworm) to Debian 13 (trixie) didn't help. I did a rollback to Armbian 25.x via backup, and this problem doesn't exist there.