Have read following post and although it had a similar title it wasn't the same problem:
[Able to connect by SSH, but not x2go](https://serverfault.com/questions/487597/able-to-connect-by-ssh-but-not-x2go)

From windows 7 client and windows 10 client at home to centOS6.7 remote server OVH
x2go client installer "x2goclient-4.0.5.0-2015.07.31-setup.exe" downloaded from:
<http://code.x2go.org/releases/binary-win32/x2goclient/releases/4.0.5.0-2015.07.31/>
PuTTY connects no problem with rsa2 key setup, both password-less keys and keys with password, sshd\_conf specified for no password login.
First time setup of x2go have yum installed x2goserver package and followed this tutorial:
<https://www.howtoforge.com/how-to-install-x2goserver-on-centos-7-as-an-alternative-for-vnc> 

When trying to connect through x2go client:

* it prompts "Enter passphrase to decrypt a key"
* If passphrase is given it prompts twice more then outputs 'authentication fail'
* It then asks for user name and user password if entered start over.

If i cancel first prompt instead of entering passphrase, outcome is the same except it skips the 2 more prompts.
Also tried changing PasswordAuthentication to yes (in sshd\_conf server side) for test purpose without key, the result was an error box that was gone in less than a second soon after my anti virus program (avg) kicked in and ripped the x2go client installation of my system for supposedly containing a unknown threat.