Help to configure QOS

[Xeross]

Hello,

I am trying to configure the QOS on my RT-AC66U with the version of Merlin 380.57.

If i'm not wrong this are the steps to follow:

First check my bandwidth:

Then enable the QOS service and in Manual, set:
Upload Bandwidth: 1.75 Mb/s
Download Bandwidth: 18 Mb/s

This should work but if i test the speeds now with nothing more on the network i get:

I don't see problems with the Download but the upload speed and latency stability are a mess, it's like all the bandwidth is limited to 0.21 Mb/s instead of trying to share all 1.75Mb/s.

I want to setup the QOS principally to stability in online games but i can't make it work...

¿Any ideas?

Thanks for your help.

 

[SnakeByte]

This test will give you more information:
https://www.megapath.com/speedtestplus/

However, it's unlikely you'll get this to work correctly. The theory is to limit your upload stream to something below your actual max... lets be safe and say 20%. So if 14.63 is your max, you'd set the qos upload to 14.63 - 2.926 = 11.704

The idea being that if your asus router gets flooded with packets to upload from all the machines on your lan, the router will drop the packets and make the originating machine resend instead of them queuing up for transport. Queues are bad because if your router needs to tell another machine something right away, it'll have to wait for the queue first. This is why latency gets terrible when you're doing a lot of uploading. There's no line cutting for the important traffic.

Jitter is related to this too -- tcp/ip manages the size of the packets automatically -- asking for larger and larger windows until a limit is reached -- then it asks for a smaller size. This repeats. However, again, if queues are involved, when the messages about when to ask for bigger or smaller get held up, your traffic starts to look like a bandsaw blade.

Dropping download bandwidth won't do much since the queues that are important are on the senders machines and only the senders have control over those queues.

Some other gotchas:

If your upstream with your isp ever drops to 11.704 or below, the asus router will begin to queue again. Many people with cable modems, or who have internet with isps that oversell their bandwidth will have a terrible time getting QOS to be reliably because their upstream bandwidth varies too greatly.

If you have a modem/gateway between your router and the isp, that modem/gateway may also be queuing packets.

Even if you get great numbers from that test above, the real-world testing I've done with running a game server in house, made for much worse lag than when I just switched everything off.

 

[Nullity]

@Xeross People often complain that the download QoS setting is quirky. Perhaps try restarting (twice?)? You may even want to forget download QoS.

Are you setting the upload to 1.75Mbit for testing purposes? You should follow SnakeByte's guideline for configuring the appropriate bitrate for QoS (~13Mbit).



@SnakeByte TCP windows do not modify packet size. They define the number of packets/bytes that are allowed to be "in-flight" (unACKed), iirc.

 

[Xeross]

@SnakeByte I can't use the megapath test because i'm from Europe and this site look like NA only. My network configuration is Moden -> Router and the ISP bandwidth normally don't fluctuate downwards.

@Nullity I used 1.75 Mb/s because the speed test showed me a total of 1.83Mb/s so to be safe i decrease it.
I'm wrong with the data types?

Look like it's wrong but it confuses me more because the download speeds seems to work fine.

Thanks for your help.

 

[indark]

@SnakeByte I can't use the megapath test because i'm from Europe and this site look like NA only. My network configuration is Moden -> Router and the ISP bandwidth normally don't fluctuate downwards.

@Nullity I used 1.75 Mb/s because the speed test showed me a total of 1.83Mb/s so to be safe i decrease it.
I'm wrong with the data types?

Look like it's wrong but it confuses me more because the download speeds seems to work fine.

Thanks for your help.

MB and Mb are 2 different unit
for online gaming, you want to minimize bufferbloat
go to http://www.dslreports.com/speedtest
as long as your bufferbloat is A or A+, you will be fine.

 

[Klueless]

I used 1.75 Mb/s because the speed test showed me a total of 1.83Mb/s so to be safe i decrease it.

Huh? The initial speed test you shared with us said 14.63 Mb/s. Based on that the 1.75 Mb/s setting you used was much too low but, based on your second speed test, it certainly demonstrated it is working. (Don't forget there's a little pop-up by the bandwidth settings so you can simply use Mb/s rather than Kb/s.) Try using the 12 Mb/s that SnakeByte suggested.

Ditto on the download, try about 125 Mb/s.

Oh. I think I just saw what you were doing wrong. Your speed tests are giving results in Mega-bits per second. Your Asus router also wants you to input in Mega-bits per second. For some reason you are choosing to convert Mega-bits into Mega-bytes? Don't. You are overthinking this.

Once you get your bandwidth limiters set up properly try it out (with your actual games). If you're still not happy (with the default QoS settings) then look into the user defined settings.

Actually, now that I reread your message, you didn't explicitly say you were having trouble with online gaming. It was more like a preemptive strike to prevent problems with online gaming?