As of 5pm local time all of my devices have not updated or shown any connection with Cumulocity IOT. I have confirmed that my devices are still active and sending data but no updates on the cumulocity front end. It appears something has changed at the cumulocity end.
is your tenant part of the us.cumulocity.com or apj.cumulocity.com cloud environments? And are your devices connecting to the platform via http?
If the answer to both questions above is yes, then this is caused by the port 80 closure that happened yesterday for both of these environments.
This was previously announced here: status.cumulocity.com
You would have to migrate your devices to use https instead of http.