The problem is there is data going from my devices to each other but how to add firewall rule to protect my data from leaving my network to the internet, For example iam using Photon for Windows and Android which supposed to work locally but how to prevent it from connecting the internet?
How to add firewall rule to a windows app to works locally only while connecting the internet? (Without selfhosting)
I can’t speak to Android but the Windows Firewall can block outbound connections for an application. It has the concept of Public and Private networks. Assuming your local network is correctly defined as Private, you can create an outbound rule blocking all traffic from a particular app to Public (which is the internet). There are numerous YouTube tutorials explaining how to do this.