Session utilises a community run network of decentralised nodes. These nodes act as the 'servers' that help route messages from user to user.
Session also uses onion-routing, so instead of relying on just a single node, we 'hop' your messages through 3 randomly selected nodes, this is what you see on your app and is referred to as your 'path'.
This path will remain the same as long as one or more of the paths do not fail 3 times and become unreachable. If they do, your client will attempt to reset your path with a new node and once established, your connection will be restored and a new path set.