AC5400X Internet Speed drop by 50% after few hours

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Hi,
I just purchased AC5400X and I am using 800Mbps from my ISP. I tested the speed through Ookla Speedtest and consistently getting 800Mbps for 1st time. However after few hours, the Speedtest dropped by 50% to 400 Mbps and I have to restart the C5400X router in order to get back 800Mbps from Speedtest.
May I know why is this happening and any solution to maintain the internet speed in long term?
Thanks
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Hey @Kevin_Z,
I was already running the latest version from the website:1.1.2 Build 20191223 rel.73956(4555)
The beta you linked, is it EU or US? or it doesn't make a difference? The download website says it does, but I'll install the beta if you say it's ok.
Also, isn't this beta older than the 1.1.2 release? at least in date they are, although I see the version is 1.1.4
Thanks
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Hi, thanks for asking.
The beta we provided in my previous reply is older than the latest version published on the website, do you mean you still have the half speed issue with your C5400X? If you would like to give it a go, this beta can work for both EU and US versions.
Good day.
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Manually configuring the max values for QoS was what fixed my speeds for me. When relying on the speed-test results, all connected devices had been artificially capped.
I think your finding got way too little attention in the thread. Thank you so much!
This is such a terrible way of implementing QoS, and the documentation around it is lackluster to say the least. Considering the price for a AC5400X, it's a ripoff.
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Thanks for your suggestion, we will investigate and see how to improve the QoS feature on the routers. While it's glad to know that your internet speed is good after manually configuring the QoS setting on the C5400X.
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