Negotiator
Member
It's p2p, which means everyone communicates with everyone (with a few exceptions*) for exchanging player movement data. The host is responsible for other stuff (syncing, or weapon pick ups in UC2 MP).It might also be an issue because the game doesn't have dedicated servers. If you're running 30 hz then that higher bandwidth is all running through the host of the peer to peer network in UC4, which means that host needs to have good upload.
I don't think it uses anywhere near 500 kbs though. People say Black Ops 3 uses about 15meg up down / hour gameplay when you're not hosting, and I remember the other Call of Duty games used to use 60kbs or so. Not a lot for multiplayer gaming.
Fully connected is p2p:
* Star topology is only used for Restricted NAT Type (3) players, which increases lag, depending on where the host is located.
I've posted detailed bandwidth measurements from my router and that was while being the party leader, along with a Party Chat session. 500 Kbps is the peak value I recorded (it's variable).
TL;DR: Everyone needs to have good upload, not just the host.