This is the first server I have built using keys but don't think that's where the error lies.

I can get FTP connection using the same Vesta CP admin login details. But other FTP accounts made within domains get linked to /sbin/nologin and return

Status: Connecting to XXX.XXX.XXX.XXX..
Response: fzSftp started, protocol_version=7
Command: open "loginuser@ipaddress" 22
Command: Pass: *******
Error: Authentication failed.
Error: Critical error: Could not connect to server
Status: Disconnected from server

/auth.log

User userlogin not allowed because shell /sbin/nologin does not exist

Dec 3 12:25:51 serverid sshd[26030]: inputuserauthrequest: invalid user userlogin [preauth]

Dec 3 12:25:51 serverid sshd[26030]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=124-170-103-63.dyn.iinet.net.au user=userlogin

Dec 3 12:25:53 serverid sshd[26030]: Failed password for invalid user userlogin from 124.170.103.63 port 56548 ssh2

Dec 3 12:25:53 serverid sshd[26030]: error: Received disconnect from 124.170.103.63: 13: Unable to authenticate [preauth]

First trial was on a fresh install with minor personal configurations (including current updates)
Second was a fresh install with only Vesta CP installed

All installs have been on Ubuntu 14.04.5 x64

Yet my current server using the same OS with minor personal configurations and some major updates which have not gone according to plan and causing some funny issues. I can create new FTP users in Vesta CP that associate with /usr/bin/rssh all work.

Thanks in advance.