@TP-Link_Deco 

Thanks, downloaded the firmware upgrade and the upgrade tool.

However login fails, and I tested logging out/in in the Deco app -- it works fine. Also works on this website for the community.

I'm using a password manager, so I'm sure I "typed it in right" :)

I'm trying on Win 10, see screenshots below.

Why does the login fail?

I'm using 

@daBowmore 

Hello,

Our engineer will email you, if you are willing to do further analysis, please check your inbox and respond.     

Thanks for your cooperation and support. Good day.

@TP-Link_Deco Many thanks, I realized that I should try without the VPN and now the authentication worked.

So far our VPN setup has not blocked any home or internet devices/services -- but clearly it blocked this somehow.

What surprises me a bit is that after running this upgrade tool with the indicated update, Deco app immediately says that there is another update available. 

Current version is 1.4.0 Build 20200324 Rel. 53529

Deco app saays that there is an update available for version 1.4.2 Build 20200725 Rel. 65637

I will perform that update as well... Surprisingly complex, when until now I was very happy how simple installation and operations was!

@daBowmore 

Hello, glad to hear that you found the solution by yourself.

Yes, we released a newer version for Deco M9 V2 previously and you may just update it to the latest now via your Deco app, there is no need to run the Upgrade Tool again.

Let us know if there is an issue, thanks a lot~

@TP-Link_Deco 

I'm following the steps to update the firmware for my 3 pack M9's. Unfortunately I fail to login in the downloaded Update Assistant. For some reason it does not recognize my TP-Link ID or password. I tried to reset, both via the App and on tplinkcloud.com but no result. I am on Windows 10, cable connection to the M9 device, and don't have a different computer to try from. 
 

Thanks. 

@Yvo 

Hi,

Is there any special software or VPN running on Windows 10? If yes, you need to turn that off first, then run the Upgrade Tool again. Below are some suggestions you may refer to:

https://www.tp-link.com/support/faq/2930/

Thanks.

@TP-Link_Deco 

A Virtual box network adapter was the culprit on my W10 PC.

@Sleater14 

Before upgrade:

Model: Deco M9 Plus

Hardware Version: V2

Firmware Version: 1.2.11 build 20190926 Rel. 55727

Just tried to upgrade to 1.4.2 with the upgrade tool on my Windows 10 device, didn't work, after the scan the upgrade tool disappears and nothing happens.

Tried the upgrade tool in compatibility mode ( Windows 8 ) and this worked just fine, and i could upgrade to 1.4.2

After upgrade:

Model: Deco M9 Plus

Hardware Version: V2

Firmware Version: 1.4.2 Build 20200725 Rel. 65637

------

Next day, upgrade to Firmware Version: 1.4.3 Build 20200917 Rel. 56749

same upgrade tool, download and unzip files in the next link, then upgrade with the upgrade tool

https://static.tp-link.com/2020/202009/20200922/Deco_M9Plus_V2_1.4.3.zip

Now you can set WPA2-PSK [AES] at the WIFI settings.

The only thing I am still missing is the possibility to change the WIFI channels, hope to see this in the next upgrade.

In busy city areas chancing the WIFI channels yourself would be a greatly appreciated option, by choosing a free or less crowded channel you will get better overall performance.

So far I am quite pleased with my Deco M9 Plus V2 

@Erik_NL You say you are on 1.4.3 using the upgrade tool. I have read in this very thread TP-link mentioning that it will not be necessary to use the upgrade tool after first time. I am on 1.4.2 and I am not getting 1.4.3 offered via the app. So are we stuck with the upgrade tool (and all the issues) for keeping our M9+ firmware updated??

@kaja69 

I also didn't get the 1.4.3. with the update on my IPad with the app,  So i used the Windows 10 device with the upgrade tool , this just worked fine for me.

If we are stuck with the upgrade tool i don't know, i am just a ( happy? ) user .