X11 forwarding problem (again)

Did you install XQuartz ?

https://www.xquartz.org

Does this work:

ssh -Y remote.Unix.system

xclock

The above work for my Mojave 10.14.4 Macbook Pro to a Linux system.

I then added the following to my $HOME/.ssh/config file

Host remote.Unix.system

ForwardX11Trusted yes

ForwardX11 yes

and that worked without any options on the ssh command line

Did "ssh -Y" work?

Did you specify BOTH

ForwardX11Trusted yes

ForwardX11 yes

in our config file?

Either the -Y or the 2 forwarding options together should work.

I'm assuming you can actually connect to the remote system, and it is just that DISPLAY is not being set on the remote system.

Have you logged out and logged back in (or rebooted) since you installed XQuartz?

If you do "printenv DISPLAY" do you get something like:

printenv DISPLAY

/private/tmp/com.apple.launchd.HDR2owme20/org.macosforge.xquartz:0

If you have tried all the above, and still failing, then it is time to add -v -v -v to the ssh command, and then look at the output to see if you can see anything related to setting up the X11 tunnel that is going bad.

Maybe if you can do the same starting from a Linux system desktop to another Linux system (maybe via a VNC connection to the first Linux system). Anyway, if you can get an "ssh -v -v -v -Y other.linux.system" you can compare the -v -v -v output from that Linux system against what you get doing the same thing from your Mac.