I have looked in the knowledge base but have not found a solution for this, and it happens quite often. I understand that if a device reboots the cisco snmp health sensor might be given a different id. PRTG will stop monitoring that sensor and show it as red (critical). Pausing and restarting the sensor, or restarting PRTG does not fix the issue. So, you have to add the sensor again. So now you have one sensor red, and one sensor green, but the "new" sensor does not have all the history of the old sensor that is now red and in alarm. It looks like if you want to keep the history of the "bad" sensor, all you can do is pause it indefinatley so you don't have a sensor in alarm, but can go back and look at the history. I have yet to see a knowledge base article that tells you how to sucsessfully move the historic data to the duplicated sensor. Just wondering if their may still be a way, or if this will be an enhancement for a future release. Thank you.