@spagettilegs 

It could be a few things.  1. placement  the further away from the source the lower speed.  Just like any client device would see.  Make sure the Range Extender is in an area with a strong signal that is between where the router is and where you need service.  2.  Band.  If your client device can connect to 5GHz you would want to use that.  You will always see better speeds on 5GHz instead of 2.4GHz.  3.  Router capablities.  Make sure the router is connected to the modem via a Cat5E or higher.  If the connection to the router is limited so will the connection to the extender.  4.  Inhernet loss.  Range Extenders (regardless of manufacture) are a half-duplex backhaul device.  This means they can only transmit in one direction at a time, either the router or the client.  Because of this one-way communication the speed will be decreased, in some cases by half.   5.  Update firmware.  Run the latest firmware available, as at times preformance tweeks are added.

If all of this checkes out there may be an issue with the Range Extender if that is the case we would need you to contact your regions support team tp-link.com/uk to inquire about a possible replacement.  they will need to confrim the troubleshooting above but that should be rather quick.  If its not determined to be the extender and just a fact of the enviorment you may want to look into Mesh as an alternative. 

@Carl 

Hi,

Thank you for your reply. I understand the basics of WiFi and I appreciate that there can be some loss over distance, interference etc. But what I'm experiencing is a 92% loss. Thats not normal. I'm standing right beside my Gigabit router, with Gigabit ethernet cables, testing the AC1200 on both 5GHz and 2.4GHz frequencies and I'm not getting past 70-80mbs.

I have indoor Ubiquity access points around my home and I'm getting upto 500mbs on them. When testing my wired internet I'm getting 800-900. So, there is some loss...I understand that. But to lose so much suggests there is a serious issue somewhere.

I should add that I have bought two of these units and they were purchased as outdoor access points to cover the front of a house (Ring doorbell 50m away) and rear of a private property. As a result I will be using 2.4GHz as opposed to 5GHz to achieve greater coverage. Even if I was to get 150mbs I would leave it at that but for the price I paid, I'm expecting a lot more than 80mbs.

@spagettilegs 

So you are trying to use an Extender to extend services across 50m?  That distance may be an issue with an AC1200 we think about 100 feet or about 30m.  Also you stated that you are using 2.4GHz.  80Mbps is actually decent for 2.4 GHz.  in optimal cricuimstances the most you can get on 2.4GHz is 150Mbps, but no one lives in optimal circuimstances.  Typically the best speed you will see is about 100Mbps but 80-90 is average.  

also you have 2 units so are you daisy chaining them?  Meaning are you connecting the 2nd extender to the 1st.  If so the same rule applys so the speed on the 2nd extender could be cut up to 1/2 the speed of 1st extender  

I’m also experiencing a slowdown when I run a Speedtest it starts off strong the dwindles to a super crawl..

the a6 ac1200 is connected right to my isp and is the main router the slowness isn't consistent but happens more often then not

@spagettilegs I'm having the same problem.  I'm right in front of the main Deco and i'm getting 30Mbps.  I switch over to my Comcast wifi and get 75Mbs.  75 is my speed.  My Nighthawk was getting full 75MBS.

@rcsmith01 I found the problem.  I'm running a Unfii USG and with Deep Packet Inspection on I only could get 30Mb/sec.  After I turned that off I can get full speed now.

@rcsmith01 

I'm having the same problem you had, how do I access the Unfii USG and with Deep Packet Inspection?

thanks