No camera image/video signal from intercom stations

Symptoms

The intercom is online and connected; calls can be made, but there is no video signal.

Open the CoCoS Management and navigate to System -> Services. Restart the service "Asterisk"
Open the CoCoS Management and navigate to System -> Devices. Restart the SIP/Asterisk Connector by enabling the checkbox in column "Restart" (Herstarten) of by switching/toggling the status from "On" (Aan) to "Off" (Uit), wait a few seconds and switch it back to "On" (Aan) again.