No persistent connection to Luminea ZX-5311-675

I bought a motion detector (Pearl, outdoor PIR motion sensor, ZigBee-compatible, with solar panel, battery and app, IP55), which probably corresponds to the Luminea ZX-5311-675. The sensor is easily integrated via ZigBee (the battery status is displayed as 100%), but unfortunately the connection goes offline again after a few hours. When I reconnect the device, the problem repeats itself.
What can I do to permanently connect the device?

Is the issue still persistent? Currently I am thinking about buying an outdoor motion sensor, thinking about this solar-powered one. Any experience or recommendation would be great.