@jubilantjesse The only solution to improve my seepds was to totally remove the Deco's and use the standard Wifi built into the ISP's modem router. I tried every possible solution and nothing woul improve the speed on the Deco. Using the deocs wifi standing right next to it I was getting half the speed compared to directly off thr ISP's wifi router. TP-Link need to fix this by separeting the 2.4 and 5.0 Ghz allowing the user to shoose which netwrok to connect to. Its clear that the software designed to autimate the wifi network slection is the cause of the slow wifi trsnafer rate. I tested this also with a LAN cable and got the same results. Half speeds through the Deco.  

@Bhavit did you try turning off the malicious content filtering Under AV? That quintupled my speed output at the device.

@southpaw I don't see any malicious filtering. What is the AV setting? 

@anipperess I don't have that set up.  This is why I am frustrated.  

The set up process is so simple and wonderful, but i can't afford to lose 80% of my speed.

For now I borrowed an Orbi RBK50 and it's been working great.

@anipperess 

The left shot is the home screen on the deco app, then click "Antivirus" on the left side. You'll see the Malicious Content Filter slider. That's what worked for me.

@ThomasOhio 

I was running into the speed issues everyone else seems to be having.  I realized the QoS settings were limiting speeds to all devices because of preferential treatment to certain devices.  You can actually set the bandwidth use for certain devices and this was my issue.  All is well now, thank you to this response!!

The issue is, that the QoS Internet Speed, does not update, when you do a regular Speed test.

I would recomend TP, that they either suggest users to update the QoS Speed, if it is significantly different from the Speed test, or simply just update it, when you do a Speed test.

Ok. I thought I was the only one having wifi performance issues.  I too have a M9 Plus setup with 3 units.  Each unit located in basement, main floor, and 2nd floor. I thought because my house was old, there may have been interference within the walls.  But even still the wifi was sub-par when I'm standing within 15 feet from the main unit that is acting as the router.  So, I then buy 3 units of the M5 thinking more units equates to better coverage.  That help a little, but like others have said, I'm getting no more than 50Mbps on wifi.  Ihad to move one of my M5 units next to my Windows workstation so I could test the ethernet.  And you know what, my speeds went from a measely 30-50Mbps to about 300Mbps on a gigabit Fios connection.  So, there is some sort of bottleneck from the TP-Link to the client over WiFi.  I'm still trying to figure it out.

I also have 2 servers and a NAS connected directly to the main M9 Plus unit via a network switch and each consistently get 700-800Mbps up/down.