I am developing a mobile app where I want to send data to other devices without servers over the global internet.
Suppose that there are 2 mobile devices with IP addresses X and Y that are on the global internet. They both know each other's addresses and want to communicate with each other without a remote server. They decided to use port A1 for that. If X will send data to Y on the port A1 will it be delivered without ISPs blocking it?
I am not that familiar with networking, only know some basics. In theory, it should deliver it without problems as long as IP's port is open and they are connected through some networks. The reason I am asking this is that I am interested in how do torrents send data to each other on the global internet without servers and static IPs, also I am not sure if there are any standard blocks that ISPs could put, for example, every ISP only allows ports from A1-A100. I know most of the rules might depend on ISP but for this example let's consider some typical normal ISP. Any explanation would be appreciated.