I connect to a server over ssh with
ssh -CX server
ok, And I launch remote graphical apps, ok. But after some minutes I get
Gtk-WARNING **: cannot open display
And I have to reset the ssh connection.
Added some outputs
$ echo $DISPLAY; echo $XAUTHORITY
localhost:11.0
$ xauth list
machine/unix:12
machine/unix:10
machine/unix:11