We use a cluster at the BESSY synchrotron to process data using XDSApp. However, upgrading to macOS Sierra stopped this dead. Logging in to the remote host was fine, but no XDS App appeared. Confounding.
The answer is that Sierra moved a component that is involved in X11 window forwarding. The X Window server (ah, SGI) runs on your own machine (as XQuartz) and the remote server just sends the updates to the GUI….sorry, did you fall asleep?
For future reference (copying liberally from the Stack Overflow answer from Christian, confirmed by Peter Edwards), we need to change one line in
On a Mac you can use:
sudo nano /etc/ssh/ssh_config
Host * :
Bingo. Thank you. Where would we be without Stack Overflow?