I used to connect GCP instance with Tabby(3rd party SSH client) and it worked so well, somehow starting recently when I tried to connect to it it always shows this error. “All configured authentication methods failed “. What I have done , was just edited the file “vim /etc/ssh/sshd_config ” turned “PermitRootLogin” and “PasswordAuthentication” into “yes” and tried using the username as “root” with relevant password to login.