The Parallels RDP Client for the Chrome platform does not allow connectivity over Gateway SSL Mode or Direct SSL Mode.
At present, the Chrome RDP client does not support connectivity over these modes. As a result, the client will not be able to connect if only Gateway SSL modes are allowed.
In most cases, the situation may be remedied by connecting over the standard Gateway or Direct modes. If Gateway SSL is a requirement, one may also opt to setup and use the HTML5 Gateway as a workaround.