RHEL-7 - How to configure session logout when using putty

Have just built a fresh RHEL-7 server. When connecting in via putty (ssh) our sessions are automatically disconnected/terminated/logged-out after 5 minutes or so.
This is a new behaviour from RHE-L6, where setting the TMOUT environment variable could be used to configure this feature.

How/where/what do we need to change to bring RHEL-7 back to RHEL-6 behaviour.
NB: We have tried playing with /etc/ssh/sshd_config ClientAliveInterval settings but this does not give us what we need.

Thanks.