Hi Manuel,
We have never encountered such a problem that attempts to NoMachine session could disconnect the VPN client. Can you tell us which VPN you’re using? Is there some antivirus on the client machine? Are you sure that you didn’t change any other configuration except for the NoMachine upgrade?
Can you please send us VPN logs showing the problem? You can send them directly to forum[at]nomahcine[dot]com, adding the title of the topic to the email subject. Thanks!