No, Custom DNS settings do not take effect immediately. Devices with an active session will continue to use the previous DNS configuration until they reconnect to the network.
To apply the new settings, the device must establish a new session. You can trigger this update on the device side by:
- Rebooting the device
- Disabling and re-enabling the cellular network interface
Alternatively, you can terminate the existing session from the User Console using the Delete session action. The device will automatically receive the updated DNS settings when it reconnects.