I updated with last firmware with this method : Download de file from the website and choose it in the browse option of the firmware update option in router menu. Now, it is possible to turn off QOS...

Can somebody who updated their router with the new firmware can tell if the problem is resolved ? If the speed is now constant and not dropping after a while ? Thanks !

@dpak I realise when I am downloading I can reach the maximum bandwith of my provider, it takes a few seconds and it depend where I'm taking the file to transfer. My question is : Is it possible that...

Same problem here. This problem was already there when I buyed this router a year ago. It took a while until I suspect this. The speed drop by half after a few hour. The only think to do is to...