RHEL7.4 Can't open display

I am attempting to open an xwindow app ( like xterm) remotely on a newly built rhel7.4 Enterprise Linux Desktop machine.

On the remote machine:
export DISPLAY=newrhel74desktop:0
xterm

Return = xterm Xt error: Can't open display

Have tried the obvious:
xhost + ( on the newrhel74desktop machine)
updated : in /etc/ssh/sshd_config
X11Forwarding yes
X11DisplayOffset 10
X11UseLocalhost no