Cant VNC into Google Compute Engine

You will need to configure three settings to all agree on the same port:

• The port vnc4server is listening on.
• A Compute Engine firewall rule to allow traffic on that port.
• The port TightVNC is attempting to connect to.

From the error message "Connection to host 8.34.210.67::5902 was closed.", it looks like TightVNC is trying to connect to 5902. Assuming that vnc4server is also listening on that port, you should add a Compute Engine firewall rule to allow that port.

Visit the Console at https://cloud.google.com/console, click on your project, then Compute Engine, then Networks. Click the "Create new" next to "Firewalls" and add a new rule with tcp:5902 set in the Ports/Protocols field.

If you're running on Centos, there is an additional step to disable the local firewall as well: CentOS Firewall Issues on GCE