Cannot connect to my distant YI cameras in Italy

I have one Indoor and two outdoor comeras in my observatory in Italy installed. Several year they worked withouth any problem. Since some weeks I receive the message “The camera is not onlin…” althoug the camera is under power. They are connect via WiFi to a GSM router.
Since they are more than 1000km far from where I live - what can I do getting in contact again?
Thank you for helping

Hello @rfa! Welcome to the forums!
The issue might’ve been caused by a sudden power interruption or the internet is slow or unstable. You can either unplug the camera from the power outlet, wait a few seconds (10 seconds?) and then plug it back. Or restart the router.
Both suggestions need you to be where the cameras are. So you might need to ask someone you trust to try these things.
Hope this helps!