Sadly it was always off for me... so this is not the problem 

Hi, I have the same problem. my 5Ghz doesn't show up on Windows 10 Pro.  2.4 ghz works fine but slow. I have Archer T2U Version1. The last driver for this version is from 2017-07-24

Are there any updates for this issue? Have somebody figured it out?

I have changed my 5G channel settings on main router to 36 and now it works.

5 Ghz showed up and I was able to connect and the speed went up.

@Kevin_Z Did you solve it? Windows 10 is the most used system, this version of the device is 5g, it's very expensive and this is the most famous trademark of network adapters. I can't figure how it's possible to release a product that absolutely doesn't work.

I bought tp-link AC600, also known as Archer T2U Nano. I have installed all the latest drivers and windows version, but i have the same problem as most of you. I see 5Ghz network, but unfortunately i cannot connect to it. Also i am getting disconected from 2,4Ghz networs really often. I don't actually know why that happens. Please help me or give me some kind of instructions!

Hello Everyone...

I just changed the Channel to 36 on the 5Ghz network and it fixed the issue.

it has nothing to do with Windows Update etc. 

im now enjoying the %ghz speed. 

Cheers

Hi all!

Had the same problem with my Archer T2UH Ver 2.0 on Windows 10 x64 2004 (latest windows update package was installed on Sept 10th, 2020). Tried changing adapter settings in various combinations to no luck, the problem was there since the day I bought the adapter.

What helped me finally get it running in 5 GHz mode:

1. Changed my router 5GHz channel to 36 (Xiaomi 4A Gigabit router model R4A, firmware MiWiFi ver 2.28.38 stable)

2. Adapter settings are as follows:

• AP Model Force BW20 - off / disabled
• Channel mode - 5G only (my wifi network is in 2.4/5 combined mode)
• Country region 2.4 GHz - #1 (1-13)
• Country region 5 GHz - #0 (36-64, 149-165) - I believe this item's value can be anything while it includes channel 36 to match router's settings.
• IEEE802.11h - on / enabled
• Prefer 5G - on / enabled
• Selective suspend - on / enabled
• Selective suspend idle timeout in seconds - 5
• Multimedia - off / disabled
• Radio - on / enabled
• Roaming - off / disabled (option #6 in my list of dropdown items)

Hope this helps!

----

А теперь по-русски.

Адаптер Archer T2UH Ver 2.0, ОС Windows 10 x64 2004 (последние обновления установлены 10.09.2020). Никак не хотел работать в режиме 5 ГГц, пробовал менять настройки адаптера в разных комбинациях - всё было бесполезно. 

Адаптер наконец-то заработал в нужном режиме после того, как я установли следующи настройки роутера и адаптера:

1. В роутере выставил номер 5 ГГц канала 36 (Xiaomi 4A Gigabit router R4A, прошивка MiWiFi 2.28.38 стабильная, роутер китаец с бесплатным плагином RuMiWiFi)

2.Настройки адаптера:

• AP Model Force BW20 - Выключить
• Channel mode - 5G only (в роутере сетка в комбинированном 2.4/5 режиме)
• IEEE802.11h - Включить
• Prefer 5G - Включить
• Selective suspend - Включить
• Selective suspend idle timeout in seconds - 5
• Мультимедийная / игровая среда - Выключить
• Радио Вкл/Выкл-Включить
• Роуминг Чувствительность - 6. Выключить
• Страна/регион 2.4 GHz - #1 (1-13)
• Страна/регион 5 GHz - #0 (36-64, 149-165) - имхо тут можно выбрать любой вариант, лишь бы был канал 36.

@Tonee Thanks a million! I posted about my problem a few days ago with no replies. I then saw that others are having similar problems. Your suggestion did the trick for me. I have a Huawei router HG8245Q.In the 5G Advcanced Network Settings, I changed Channel from Auto to 36 (even though there's now a message in red saying You are advised to set the channel to Automatic.

My 5G network from the router immediately appeared and I can connect to it and Speedtest reports 105Mbps for download (not bad considering that my subsciption is for 100Mbps!)

Thanks again!

Regards

Rick

@Victor01 Guys, I am victim of same issue , today my %G network are whowing on but not connecting.

I can use 5g on mobile but not on PC using TP AC600

Have to use 2.4 Ghz at slow speed

kindly assist