Comment # 3 on bug 1024652 from Filip Ko��odziejczyk

Not sure if it is the same bug but it seems to me that it is.

I noticed it while looking for a solution with flatpak apps.
Basically when I start my laptop and start a flatpak immediately before WiFi
connection is established it starts without a problem but when WiFi is
connected I get "Cannot open display" error.

Turned out that "echo $XAUTHLOCALHOSTNAME" and "hostname" commands outputs are
different. Resetting a hostname in Yasts Network Settings solves the problem
but only until reboot.