Hello Ihave been using my archer c6 v4 for around a year. 

I have incountered a problem ever since I have used the router I has limited bandwidth of around 50% of which is advertised in the routers box and tp links website. I have onces  reach customer service but the solution presents were not helpful.Ithey told me to test on high-end devices so I can see if it's my device's fault.i have since  tested on many devices including high-end Android,ios and also many mid to low end devices but the problem still persists.after many firmware updates this issue has never been fixed I hope I can find the solution in thread