If we are getting connection time-outs when using iTest VNC, but not when using a native VNC viewer, we need to examine our PC's firewall rules. It's very likely that the iTest program and its traffic are being blocked.
In Windows machines we need to set two inbound rules:
One rule for TCP and one for UDP. Allow any local/remote address, protocol, port, and computer or user access to iTest - and be sure to apply these rules on all profiles (domain, private, public, etc...).
Also, currently the VNC session requires encryption to be set to "always off" or "preferred off" and authentication to be set to either "none" or VNC password".