Question about Connection from one of my device to another

LeonSKennedy

1. I can directly connect from one of mine device to another from the devices list. Without password. But question is, will this cause internet data flow(even when all of my devices under same LAN network(same router))?
2. If first point is a yes. I may need think about LAN connection. I already worked out input the LAN IP to connect. But it always require password, either random one or private password. Is there a way to bypass the permission check make it same as 1st point?