IPA no users can log in: Connection closed by <ip-address-of-server>

Issue

• When any IPA users try and log in their session gets logged off immediately with message:
  Connection closed by 192.168.1.2
• In /var/log/secure see messages:

Apr 18 12:04:03 ipaserver sshd[15824]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=192.168.122.1  user=testu1
Apr 18 12:04:04 ipaserver sshd[15824]: pam_sss(sshd:auth): authentication success; logname= uid=0 euid=0 tty=ssh ruser= rhost=192.168.122.1 user=testu1
Apr 18 12:04:04 ipaserver sshd[15824]: pam_sss(sshd:account): Access denied for user testu1: 6 (Permission denied)
Apr 18 12:04:04 ipaserver sshd[15824]: Failed password for testu1 from 192.168.122.1 port 37864 ssh2

• When we try to ssh to the client it is not working.