Up until last week, I have been able to open X11 windows just fine on the remote machine. Suddenly I have not been able to.
I connect to the machine with
$ ssh user@remote -Y
I am running OSX Sierra 10.12.6 and XQuartz.
When I connect to the remote machine, I attempt to launch an X11 window and get the error message.
$ xeyes
connect localhost port 6000: Connection refused
Error: Can't open display: localhost:10.0
Following the instructions in other questions, I have reinstalled XQuartz, reset network settings and disabled my firewall and none of these have solved the problem.