How to setup low priority to download

[Karnof]

Hello everyone.

I have a very limited WAN bandwidth at home(<4Mbits/s) and as soon as steam try to download something, it use most of the bandwidth and I can't watch YouTube or anything else.

I would like to limit steam's DL bandwidth dynamically, and only DL, not game trafic. This way steam use full speed when I'm not using internet, and throttle down when I need it.
I know how to limit it manually in the client parameters, but it's a bit impractical as I'll have to set it every time.


I have a Syslink router with OpenWRT and QoS package installed.
My idea is to set a low priority to steam DL ports and ideally give a high priority to game trafic.
Steam use those ports :

Originally posted by steam:

To log into Steam and download content:

HTTP (TCP remote port 80) and HTTPS (443)
UDP remote port 27015-27050
TCP remote port 27015-27050


Steam Client

UDP remote port 27000-27100: Game traffic
UDP local port 27031-27036: Remote Play
TCP local port 27036: Remote Play
UDP remote port 4380

Dedicated or Listen Servers

TCP local port 27015 (default): SRCDS Rcon port
UDP local port 27015 (default): gameplay traffic

Steamworks P2P Networking and Steam Voice Chat

UDP remote port 3478
UDP remote port 4379
UDP remote port 4380
UDP remote ports: 27014-27030

Obviously I'm not gonna limit HTTP and HTTPS, but if I limit UDP and TCP 27015-27050 it seems I'm limiting half of game trafic as well.

I tried it anyway and it doesn't seems to limit anything, so I'm assuming steam use classic HTTP(s) ports in order to DL?

Did someone managed to do what I want to do?
If there is other ways to dynamically limit steam DL, I'll be happy to hear about (ideally without third party software like Netlimiter)

Thank you.

[Muppet among Puppets]

Steam tab, settings, download. You can choose in kB steps

Youtube can run with a little, so if you set steam to 3Mb, it should be fine. And still fast enough to keep it like that

[Karnof]

Originally posted by Muppet among Puppets:

Steam tab, settings, download. You can choose in kB steps

As I said, I want it dynamically, not manually set bandwidth limit every time there is a DL.

[Muppet among Puppets]

What happens if you limit to 3?

[Karnof]

It depends of what I'm doing, and that's not really the point.

In fact, as I have a very low bandwidth, I want every kb to count.
Always limiting to 3 means DL in 10 hours instead of 7h30, and it's not optimised.
And having to turn On and Off this limit when I'm watching netflix downstairs or when somebody else at home is using internet is annoying.

That is why I want something that regulate itself.
I already have something similar with a raspberry pi that synchronize file from a VPS (rsync command). The protocol is set to low priority and only use unused bandwidth. The only downside is a bit of ping but not that much.

[Karnof]

Funnily enough, steam's forum have loads of topics talking about having faster download and higher priority, but nothing about giving it less priority over WAN bandwidth, at least dynamicaly.

I have myself found another solution but it requires to use another PC and setting all his internet trafic (at least HTTP(s)) to low priority. Then, after download finished, I can use beta steam client to automatically download games over LAN.

It does the job but I'm more concerned about my electricity bill now... and unfortunaly steam(cmd) doesn't work natively on raspberry pi.

If someone have another way to achieve what I want I'm all ears !