This is related to this question PCs in same network can not communicate
My real problem was that I have a web application I want to test running in PC1 but I noticed I could not even ping the machine.
By opening firewall ping is possible.
By opening a rule for the port of the web application I need to access, I can reach my web application.
It is not clear to me how can I safely add a rule to the firewall so that I don't have problems from public network.
I tried to specify a rule to open the port to be accessed from a specific address only, but it required the connection to be secure.
So how can I configure a safe rule in my case?