Block Grafana from accessing the internet


I am using Grafana on a Raspberrry PI with a LTE dongle attached to it, therefore i drastically need to reduce the internet communication to prevent running out of my monthly data volume.
It seems that Grafana causes around 20-30MB of traffic every day by just idling withouth being accessed.

Does anyone have experience with cutting of internet access to the Grafana-Server, is it still possible to run in “offline” mode? Or maybe some recommendations about reducing the communication?

Thanks in advance.