Question about latency and QOS

[porter44]

I’ve been trying to improve latency to make voip run a little better on my router. I’ve been testing different configurations while doing a speedtest and pinging google and then checking to see how it affects the ping time. When I use the traditional QOS setting, the ping times max out around 160ms with an average around 55ms under load. When I change the QOS to ‘Adaptive’ the ping times max out very different. I get a max of 1400ms and average around 115ms. I’m wondering if I’m doing something wrong to see such a significant difference. I have the upload and download bandwidth set the same for both types of QOS. My unloaded ping times are around 25ms on both types of QOS.

 

[Gouldin]

what bandwidth does your internet provide? If your ping increase that much then it's overloading the connection which would imply that you have the bandwidth set too high for your connection.

General rule of thumb set your limits to 15-20% less than your overall bandwidth to see any benefit.

 

[porter44]

what bandwidth does your internet provide?

My dsl internet bandwidth is 2.5Mbps down and around 0.4Mbps up.

If your ping increases that much then it's overloading the connection which would imply that you have the bandwidth set too high for your connection.

I have the download bandwidth set at 2Mbps and the upload set for 0.32Mbps. When I enable the ‘traditional QOS’ setting and do my testing the speedtest shows my connection pulling the full 2.5Mbps regardless of what value I enter for the download bandwidth. I listed the ping times for this setting in my first post. 160ms spikes with and average time around 55ms


When I enable the ‘adaptive QOS’ setting I get very different results. From what I can tell, the download and upload bandwidth settings that I enter seem to work properly. The ping times however are terrible. 1400ms spikes with a high average time as well.

 

[Gouldin]

That'll explain it.
QoS never did much for me either when my VDSL was 22mb down and had 1mb upload.

The QoS on Asus devices doesn't scale down very well at all for low numbers, which is where it's essential.

It works, but just doesn't handle traffic spikes anywhere near fast enough to kick in in time and be useful. You aren't doing anything wrong unfortunately.

On my old connection I found no useful solution on the asus routers.
The Netgear xr500 netduma routers handle low speeds quite nicely though.

 

[porter44]

The part that still doesn’t make sense to me is why does the download bandwidth setting in the ‘traditional QOS’ not work. It doesn’t matter what number I enter for that setting it maxes out the download bandwidth. For example if I put the download bandwidth at 1Mbps it will still max out my download bandwidth at 2.5Mbps. Or even if I take it a step further and go into the priorities settings and set Highest, High, Medium, low, lowest all to limit my download speed to 80% of the 1Mbps download setting I entered it will still max out my download bandwidth at 2.5Mbps.

 

[ColinTaylor]

What router model so you have? What firmware version are you using?

Traditional QoS was generally regarded as "broken" for many years. Asus subsequently introduced Adaptive QoS and as far as I'm aware never fixed Traditional.

 

[porter44]

What router model so you have? What firmware version are you using?

Traditional QoS was generally regarded as "broken" for many years. Asus subsequently introduced Adaptive QoS and as far as I'm aware never fixed Traditional.

Asus RT-AC68U merlin 380.70

From what I can tell the Traditional QoS upload limit setting works properly but the download limit does not. I can't prevent the download from saturating my connection... Even with the missing functionality I still get much better latency than trying to use the Adaptive QoS. The latency spikes are almost 10x worse. 1400ms compared to 160ms

 

[ColinTaylor]

Asus RT-AC68U merlin 380.70

Your firmware is years out of date. Try updating to the current version and it might now work.

Alternatively try using John's Fork. It lacks some of the newer features (particularly Adaptive QoS) but Traditional QoS is fixed in it.

 

[K-2SO]

Asus subsequently introduced Adaptive QoS and as far as I'm aware never fixed Traditional.

Works pretty well for bufferbloat mitigation purposes on last 4-5 Asuswrt and Merlin firmware for RT-AC86U. Not sure about RT-AC68U though. Set on 90-95% down/up generates constant A/A+ ratings on DSLReports, if the test can be trusted. Adaptive QoS may prioritize the traffic better, but generates constant >500ms bufferbloat spikes near line saturation speeds.