Hello,

1. SFTP root login.

I use my macbook to make connection to Oracle VM (I can not use windows programs).
Via terminal, I can login as VM user (ubuntu) via private key, and then using command sudo -i  (or sudo su), i will switch to root user.

But problem is with SFTP login.
If i connect with my user (ubuntu) and private key using File Zilla client, i can not edit any files or folder where root user is owner.

If i login as ubuntu at SFTP and try to open root directory, this error will show up:
Command: cd “root”
Error: Directory /root: permission denied
Error: Failed to retrieve directory listing

I was try with CyberDuck FTP client.
To log in as ubuntu (my-user) and then use the terminal to (sudo -i) to transfer from ubuntu to root. But that was not work to.

How can i login as root user to SFTP using File Zilla?

I was try to follow this documentation:
Oracle Cloud Infrastructure – How to setup SFTP to chroot Jail with SSH keys (Doc ID 2520513.1)
But that did not help me.

2. Reinstall system – Instance

I have made some mistakes at my Ubuntu OS, and I will like to reinstall my VPS OS (but to keep instance, ip (network), firewall etc..).

I was not able to find an option for OS reinstallation, but I made a clean backup of my boot volume (the same day when i was create VM).

How i can restore that backup and have clean Ubuntu OS?

I have restore backup, and create boot volume from it. Then i detach old volume, and attach new boot volume following this doc: https://docs.oracle.com/en-us/iaas/Content/Block/Tasks/attachingavolume.htm#Attaching_a_Volume

And here is image how it look like now: https://ibb.co/s9PC9BF
https://ibb.co/9sxZxTV

But still I*am not able to start my instance. it say:
Unable to start instance: Operation cannot be performed. Boot volume is not currently attached to the instance.

I hope that termination of instance and creating new is not only solution, because that will change my ip too.