cox internet connection unstable

I work at home using the Cox internet.  Last year, the connection was unstable sometimes, I bought a new Cable Modem, a technician came to check and didn't find any issues.  I accepted the fact of unstable connection sometimes. But recently, almost every morning, the connection is unstable, the internet frequently disconnected.  I don't think it's modem problem,  the internet connection is fine in the afternoon and night.