MongoDb connection lost at first request

I have an application that is already running on PythonAnywhere for a long time with a connection to my MongoDb server (cloud). I now deployed a new version, which is running on my DEV environment without issues and the log shows that the connection is created. I added some PRINT logging which shows that the find_one instruction that always worked and works in DEV, now does no longer work in my PythonAnywhere environment.

error logging ends with this message: myvirtualenv/lib/python3.9/site-packages/pymongo/", line 250, in _raise_connection_failure raise AutoReconnect(msg) from error

Did you update the mongoDB server or the PythonAnywhere web app?