If I have several computers on my home network and I have not set any explicit QoS rules on my router, how is bandwidth allocated? For example, if computer 1 is downloading a torrent at max speed and a second computer starts a download, how is the bandwidth allocation between the two determined? Thanks!
There are a lot of variables that could cause that situation. Were both machines on the same physical link (ethernet vs wifi)? Changes to their RTT could influence it. The only thing I could really add is that you have found the reason QoS mechanisms exist, lol.
edit: I guess I can add this: if computer 1's download was from a host that has longer total round trip latency than computer 2's download, computer 2's download will return ACKs quicker and thus get PSH packets with data quicker than computer 1. This will lead to it filling available bandwidth more easily.