Yes. Didn't help.

However suddenly one laptop was able to connect to 2 other windows boxes (even though other Windows machines cant).

This tells me it's not ZT fault, but rather everlasting update and restriction nonsense from windows is a culprit

Pretty much this ^^ You've given no detail that differentiates your issue from all the other general troubleshooting advice out there already, nor do you say what you've tried to debug it.