When I try to login to my VPS using SSH and SFTP it's not connect to the server. Then I power off and power on the VPS by the VPS provider control panel (digital ocean). Once it boot up, first few seconds I can access the server, after few minutes left I can't.
This is a Ubuntu 14.04.2+Nginx1.6.2 server. I use CSF,Fail2ban. What is the reason for this matter?
My /var/log/auth.log.
Apr 13 22:49:23 my-Server sshd[1569]: error: Could not load host key: /etc/ssh/ssh_host_ed25519_key
Apr 13 22:49:20 my-Server sshd[1071]: Server listening on 0.0.0.0 port 2200.
Apr 13 22:49:20 my-Server sshd[1071]: Server listening on :: port 2200.
Apr 13 22:49:22 my-Server su[1477]: Successful su for newrelic by root
Apr 13 22:49:22 my-Server su[1477]: + /dev/console root:newrelic
Apr 13 22:49:22 my-Server su[1477]: pam_unix(su:session): session opened for user newrelic by (uid=0)
Apr 13 22:49:22 my-Server su[1477]: pam_unix(su:session): session closed for user newrelic
Apr 13 22:49:23 my-Server sshd[1569]: error: Could not load host key: /etc/ssh/ssh_host_ed25519_key
Apr 13 22:49:26 my-Server sshd[1569]: Accepted password for root from 124.43.254.193 port 52514 ssh2
Apr 13 22:49:26 my-Server sshd[1569]: pam_unix(sshd:session): session opened for user root by (uid=0)