@Manolo86 

It doesn't do much anyway. The issue persists even with the firmware, just not -quite- as low.

Are there any updates on this issue?

I have same issue since i replace my router wiuth c5400x. my internet connection drops from 150mbps to 60mbps after a few hour

@dpak 

I just got this router the other day from Amazon and I have 400mbps down 20mbps up service from Spectrum. I am having the same problem, I cannot get over 320mbps on the download side and the upload side is around 17mbps, has there been ANY resolution to this problem? My pc is connected via ethernet to the router.

@Chaz have you tried the beta firmware they posted earlier here?  I know others have tried it and it didn't fix their problem but it did for me. I installed it and had my router automatically reboot each night for about a week and my speeds are maintaining. I no longer get the drop in speed after an hour or whatever time period. I too have Spectrum. I have their gig service and my speeds stay around 940 down and 40 up. 
 

On a side note, as a "gaming" router if nothing more, there is no excuse for this situation going on this long without a full release firmware that maintains the integrity of this router. 

@jhawk27 

I can't because the link is dead now. That's the problem. I'd like a new link if possible.

jhawk27 wrote

@Chaz have you tried the beta firmware they posted earlier here?  I know others have tried it and it didn't fix their problem but it did for me. I installed it and had my router automatically reboot each night for about a week and my speeds are maintaining. I no longer get the drop in speed after an hour or whatever time period. I too have Spectrum. I have their gig service and my speeds stay around 940 down and 40 up. 
 

On a side note, as a "gaming" router if nothing more, there is no excuse for this situation going on this long without a full release firmware that maintains the integrity of this router. 

@Manolo86 sorry guys. Didn't realize the link was dead now. This has gone on way too long with no long term resolution. Come on TP Link. You guys make quality products. Back them up with support. Let's go. 

@jhawk27 

I was trying to find the link, but it no longer works, Currently the only thing that has help was to have the qos settings to general and no devices are set.. 

@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 the QOS is not really compatible with Speed test and cannot manage it in the right manner ?  Even if they put this test in their web application.  If TP-Link do not respond to our request, maybe it's because there is a real problem with this router ?