I tried to use wireshark using a remote logon to a system. This failed with

This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

There was an easy fix.

ssh -X u350@10.1.0.5

Use the -X option – simple.

I also saw references to the file/etc/ssh/sshd_config on the remote machine and the file needing X11Forwarding yes

If you use the following in a command window

echo $DISPLAY

it should say something like

localhost:10.0