I am having this issue with new Ubuntu installation on one of my friends. I am trying to access his laptop and I cannot access from my laptop. Previously it was working perfectly and I can connect to other friends but not with this one. He is running Ubuntu 16.04 LTS and installed Teamviewer using .deb package.
When I enter his user ID, it simply throws a pop up with:
`Connection could not be established.
Reason Unknown error `
I searched on the web, but it didn't have proper answer. Can any one help me with this on Ubuntu?