Comment by pl4nty

Microsoft Store and Xbox games/updates are distributed with a proprietary P2P protocol, which also includes ISP appliances. afaik it's the largest P2P network in the world. https://learn.microsoft.com/en-us/windows/deployment/do/mcc-...

Steam recently introduced LAN-based P2P to complement their significant appliance/CDN infrastructure, but idk if anyone has pulled it apart yet. and I don't think it does tunnelling like the msft network