If you you are in the local LAN and havent the right IP or DNS Name on the External Tab in Linkus to register, you get an Server not found (1) error. Manual Login and with the E-Mail from the Linkus Server.
If you use an FDQN for the external connection you need to setup Split DNS or if not needed from external use also the local IP.
Must be an Linkus problem from the App Center Version 2.10.3 - was working before with the yeastar. (22.214.171.124)