Link boost refers to using both Wifi & 4G. There's another version using both 5GHz & 2.4GHz Wifi.

Link to 256 QAM:

https://7signal.com/802-11ac-migration-part...-about-256-qam/

1. Set the Wireless Mode to N/AC mixed
2. Set the Channel bandwidth to run at 80MHz

1. Set the Wireless Mode to N/AC mixed
2. Set the Channel bandwidth to run at 80MHz

It depends on your device, most smartphones are on AC1200 adapter only.

Most smartphones released after year 2015 are using 2x2 SU-MIMO chip already except those low end smartphones. Flagship smartphones released after year 2016 (e.g: Samsung Galaxy S7) are using 2x2 MU-MIMO chip (802.11ac Wave 2) most of them are powered by the Wi-Fi chip leader + hegemon Broadcom (Broadcom Numba Wan).

But in recent years still have some guilty smartphone vendors use 802.11n single-band 1x1 chip on their low end smartphones to cut cost + clear inventory like Huawei Nova 3i (2018), Huawei Y5 (2019), Redmi 7 (2019), Realme 3 (2019), Realme C2 (2019), Samsung Galaxy A10 (2019), Samsung Galaxy A20 (2019).

TP-Link a freaking networking company usually will also use their old inventory of 802.11n chips on their low end smartphones like Neffos C9 and Neffos C7. Well at least TP-Link did put a 802.11n dual-band chip into their mid range smartphones like the Neffos Y7. 802.11n dual-band chips were very popular among flagship smartphones around year 2011-2013 before smartphone vendors adopt the 802.11ac Wi-Fi standard, most notably used by the original iPad (2010), iPad 2 (2011), Samsung Galaxy S2 (2011), Samsung Galaxy Nexus (2011), Samsung Galaxy S3 (2012), HTC Amaze 4G (2011), HTC One X (2012). Yes, they all have 802.11n dual-band Wi-Fi.

Smartphones released before 2013 are using 1x1 SU-MIMO for example that flagship Samsung Galaxy S4, if it's 802.11n then the max data rate on 5 GHz is 150 Mbps, if it's 802.11ac like the one can be found on HTC One M7 (2013) then the max data rate on 5 GHz is 433.3 Mbps. FYI HTC One M7 is actually the first smartphone with a 802.11ac chip powered by Broadcom Wi-Fi + Bluetooth + FM radio combo chip all the way back in 2013.

Samsung began to support 2x2 SU-MIMO (802.11ac Wave 1) in year 2014 on their Samsung Galaxy S5. In year 2015 Samsung continue to put 802.11ac 2x2 SU-MIMO Broadcom chip into their Samsung Galaxy S6 again. Apple began to support 802.11ac 1x1 SU-MIMO Broadcom chip in year 2014 on their Apple iPhone 6 and 6 Plus. In year 2015 Apple only began to support 802.11ac 2x2 SU-MIMO Broadcom on their Apple iPhone 6s and 6s Plus. With 2x2 spatial stream all these smartphones can reach a theoretical data rate of 866.7 Mbps. It's year 2019 now but so far no smartphone in the world supports 3x3 MU-MIMO Wi-Fi radio yet.

On the side note, Samsung Galaxy S10 series (2019) are the first smartphones to support the next generation 802.11ax Wi-Fi standard.

I have 300Mbps download and 50Mbps upload speed, via Ethernet LAN. When I use TP Link TL-WR1043ND wireless router, max speed only 90+ Mbps download and 50Mbps upload (2.4GHz).

I thought 2.4GHz can reach 300Mbps?

Set your 5GHz to run at 80MHz. Not 20MHz, not 40MHz, not auto, not 20/40/80MHz but instead set it to 80MHz only. Don't ask me how, read the manual of your router
Also, if you can afford to pay UniFi 800Mb/s, you can afford to buy a better router
All stock routers from TM/Maxis/Time is crap

Get at least ASUS RT-AC66U B1
Like you, I'm also using UniFi 800Mb/s. I can get 600Mb/s on ASUS RT-AC68U, RT-AC86U & GT-AC5300. RT-AC66U B1 is basically the same as RT-AC68U so you should be able to get at 600Mb/s on WiFi as well
Below is a screenshot of the Speedtest on WiFi



No
You can only reach 300Mb/s on 2.4GHz if your WiFi receiver is 3x3 & running at 40Mhz

Most devices only supports 2x2 & that limits you to 150Mb/s which translate to actual speed of 90 ~ 100Mb/s

1. If you want full 300Mb/s, you need 5GHz running at 80MHz
2. Dump that WR1043ND. That's a very old router. My suggestion to at least get an ASUS RT-AC66U B1

Xiaomi only says it support Wireless AC but didn't mention whether it is 1x1 or 2x2.

For cheaper phones, assume a maximum speed of 500Mbps.

https://www.devicespecifications.com/en/model/74615336

this site mentions it's 2x2

Your WiFi Adaptor using USB 2.0 or 3.0?

Thanks

What's your stock router model?

Thanks.

Can you check your Wi-Fi Adapter settings there.
Did you install the correct drivers?

Thanks.