The Devices App URL can be configured here. This URL is used to establish a websocket connection to the Devices App and register there.
The Format is: wss://[dns-ap-platform]/[system domain]/devices/sysclients
If the connection between the device and the Devices App is up, there is "Up, X sessions" shown.
If there is someone browsing on the UI of the device through the Devices App, the session counter is increased.
Implicit changes of the Devices App URL
When a PBX is connected to a Devices App service instance, it will send the URL used to connect (and which is configured in the URL property of the respective App object) to the instance. Devices will then deploy this URL to the Devices App URL setting of all devices registered. This way it is possible to change the URL without touching each device separately (see Change of IP address/DNS name in PBX object ). Therefore, if you change the Devices App URL it will be silently changed back again. Rather change the URL property in the Devices's App object.