@Whocarestp 

"If you set up total bandwidth is 1000Mbps download/upload, remove all the high priority devices, it will not hamper the internet speed."

Do you have any proof to back that up? Will it not intervene in any way to "even out" traffic/bandwidth between devices if you will, or prioritize certain types of packages?

If I take a laptop and plug it into the first Deco M4 in the "chain" then the speedtest results are as shown on the left (QoS enabled, set to 1000 down and up, all priority devices removed.

If I take that same laptop, same cable and same speedtest server and plug it into the last cable before the first Deco M4 (so no Deco M4 connected) then the speedtest results are as shown on the right side.

Notice the difference especially in upload speeds?

Now you could argue that it can be for other reasons as well, but since there's no way to turn of QoS how am I supposed to be able to debug this behavior?!

Before you suggest I factory reset everything I'd like to remind you that a lot of people, myself included, have home automation devices set up and connecting all of those to a new wireless ssid would take literal hours.

You gotta ask yourself: how hard could it possible be to include an off-switch on either the web interface or the mobile app?

@TP-Link 

Also I've seen you respond to inquiries much like my own in the same fashion for over a year. What is it going to take for you to escalate this to your dev-team or similar to finally get this resolved? It's preposterous!

@TP-Link 

Same issue here. I'm a Deco E4 user cannot update/disable QOS and already using the latest firmware/Deco mobile apps.

I need to utilized my bandwidth upgrade from previously 100mbps to 300mbps but the QOS settings option is only 0.01-100mbps and QOS cannot be disable.

@TP-Link 

Thanks for the clarification. So in this case, I can add 1 M4 (as primary, connected to ISP modem) and use the existing 3 E4 (as satellite units)?

so i can utilize my new 300 mbps internet speed.

@Whocarestp @TP-Link

Today I've bough TP-Link Deco M4's, configured everything (SSID and password the same as in previous router) and enabled QoS from the start. Everything worked fine until I went to use my Macbook pro and by some magical reason it could not connect to network, tried everything that I could find on the related issue with Mac, but nothing helped. Someone wrote in a post that enabling QoS on router helped the issue, so I thought to disable the feature but long and behold no disable button or option to reset values to initial state. After googling and finding this and couple related posts I've deleted and recreated my network from scratch, and Mac without any issues connected to the network.

I have no idea what was the cause of it, is it QoS or by recreating network from scratch resolved something, but without the button I cannot test this. Maybe it is a good incentive for dev's to spend some time on adding a disable button or allow to reset values at least to one app, web or mobile. Because something basic as this on/off should be included by default, especially when the feature does not work initially until you configure the values, like how?

I've decided to switch the deco's to access point mode instead of router mode, which greatly increased my download- and upload speeds.

The reason for this is that, next to not being able to manage QoS properly, port forwarding also didn't work as intended. With such shoddy software I've decided to use as little features as possible, which is why I killed the router features altogether.

They look pretty, installation is pretty straight-forward, the wifi coverage is good enough, but the software is terrible. Too bad you can't seem to align your hardware with your software.