Slow non-cached download (steam)

[inDane]

I've installed a proxy cache based on https://github.com/bntjah/lancache . Some things are different in my setup, i'm using a second server for DNS which is using DNSmasq.

The problem is, that non-cached downloading i.e. from steam is terribly slow. This is, in my opinion due to the fact, that only one connection is made from my computer to the cache-server and that nginx would need to finish serving that connection before it can do anything else (I read that somewhere). A download without the caching server from steam would open something like 20 connections to have maximum downlink saturation. The 20 connections belong to the same net, lets say 155.166.177.0/24. A non-cached download via the caching server is about 7% of the possible download speed, but nginx seems to open more than one connection to the steam cdn.

Do I think in the right direction? How can I overcome this limitation?

Thanks in advance.

(i don't use QoS on my gateway.)

[inDane]

Two pictures from client-view
direct download:

non-cached download via lancache: