sshd: User xxxx from gateway not allowed because not listed in AllowUsers

Issue

• Received following error message during ssh login:

  client : 
  Permission denied, please try again
  
  server :
  sshd[xxxx]: Failed password for invalid user xxxxx from xx.xx.xx.xxx port xxx ssh2
  sshd[xxxx]: Connection closed by xx.xx.xx.xxx port xxx [preauth]
  sshd[xxxx]: User xxxxx from gateway not allowed because not listed in AllowUsers
  sshd[xxxx]: input_userauth_request: invalid user xxxxx [preauth]
  unix_chkpwd[xxxx]: password check failed for user (xxxxx)