wifi speed drops

I tried to explain it more than once but you don't seem to understand. After you plugged the external usb wifi dongle into your pi, did you enter Kodi's wifi setup screen to enable it ?

What is the make and model number of your usb wifi dongle ?

What steps did you go through to enable it in the software ?

software = libreelec

You need to disable the Raspberry Pi's internal wifi and use a supported USB WIFI device. That device may (will) need to be setup properly in order for it to work. There is also another device which was mentioned in other threads but I forget the name for it. It's 100% plug n play according to the poster.

Your Archer T2U has a MediaTek MT7610U Chipset. I'm not sure if it's supported by Libreelec (Linux)

yes i got to Problems with Wifi on RPi 4 in 2,4 Ghz it´s very slow 1-6 Mbps

In 5 Ghz i got 48-30 Mbps only in 2,4 it´s slow

Wifi Sticks for Rpi:

CSL WLAN Stick 300 Mbit/s USB WLAN Raspberry Pi Realtek RTL 8192CU Chip

EDIMAX EW-7811UN Wireless USB Adapter, 150 Mbit/s, IEEE802.11b/g/n supported by Libreelec

USB Wireless Adapter MediaTek Ralink RT5370N 150Mbps 2dBi Antenne WiFi Dongle

Ralink 5370 Wifi Dongle USB 2.0

Quote from megaprime421

hey, hi do you achieved to change to 5ghz on libreelec? Because I don't see any options how, (sorry if its silly question)

Your router is 2.4

you need a new good Router thats suport 5.0 Gh like FRITZ!Box 7530 its support new WPA3 in beta Firmware

everything else is useless because the Router creates the wifi and not a wifi extender, wifi stick etc.