I do not know how people count here, but your speed also relies on receiving device. For example lot of smartphone connecting on like 2.4HZ max, and max I see was real speed of 75Mbps and that's it, nothing more than that really. Be sure to keep it checked.

Why my wifi so slow?
Since many Unifi users have got Turbo speed now, more and more people are asking why their wifi is so slow. Unfortunately many are misled by those AC1200, AC1750, AC2400 numbers so here's a guide to what actual speed you can achieve. Now, just to clarify, this is about WiFi speed not internet speed but in order to get max internet speed, you first have to get your wifi in order.

tl;dr Maximum WiFi Speeds
Here's a tl;dr of the max wifi speed that I've tested. Remember, in order to get max speed, your device must equal or better the wifi router.

	Phone	Laptop	Tablet
2.4Ghz 2x2	91.57 Mbps	92.1 Mbps	-
5Ghz 1x1	240.53 Mbps	244 Mbps	-
5Ghz 2x2	343.66 Mbps	357 Mbps	518.79 Mbps
5Ghz 3x3	-	875 Mbps	-

Gigabit Ethernet: 934 Mbps (for ref)
Faster speeds coming when I test the faster wifi routers.

AC Rating
The first thing, those AC numbers or Rating. These are there to impress help consumers.

The numbers give an indication of the speed of the router but they're mostly there because marketing needed a shorter way to describe the router. So instead of "2.4Ghz 2x2 MIMO and 5Ghz 2x2 MIMO", they use AC1200. Much simpler but just remember no way you'll get 1200Mbps from it.

TM's TP-Link C1200 as an example
Many people have this wifi router since it's a freebie from TM. It is AC1200.

Max 5Ghz link speed: 866Mbps (2x2 5Ghz wifi streams)
Max 2.4Ghz link speed: 300Mbps (2x2 2.4Ghz wifi streams)

So 866+300 = 1200 (yes, marketing did the math)
2x2, 3x3 MIMO
If you wondering what is that 2x2 wifi streams. It's something like this.

2x2 means 2 transmit and 2 receive.
MIMO (multiple in/multiple out) means the wifi can receive,send more than one wifi stream at the same time. Everything is MIMO now.
streams are sometimes called chains. Some people use the term antenna. Not wrong. One stream needs one antenna to transmit. Then you look at the C1200 which is 2x2 but it has 3 antennas. How leh? That one I explain later.

Which brings us to the speed of each stream. It can be more but let's stick to this for now.
One 5Ghz stream = 433Mbps
One 2.4Ghz stream = 150Mbps

Therefore for the TP-Link C1200, for 5Ghz, 2 streams is 2 x 433Mbps = 866Mbps.
Same for 2.4Ghz, 2 x 150Mbps = 300Mbps.
Add these together and you'll get the 1200 in AC1200.
Your laptop, phone
Alright, so your laptop and phone also has the same things. 1x1, 2x2, 3x3 MIMO. In order to get max speed, your phone must equal or better the wifi router.

Now, this is where a lot of questions arises. Some people might have a great router but their laptop or phone not so good. And vice-versa.
1. Most phones are 1x1
2. Some only have 2.4Ghz, no 5Ghz
3. Most laptops are 2x2
4. Some are 3x3
5. Cheaper laptops only have 2.4Ghz

So you see, if you connect a phone with 5GHz AC 1x1 to a C1200 2x2, the link speed will only be 433Mbps.
Link Speed vs Actual Speed
You might think, 433Mbps link speed is damn good already. But when you try, your speeds are much slower. Yeah, you'll never get full link speed. Why? Actually I'm not entirely sure so I'll leave that to Google.

https://res.cloudinary.com/soonwai/image/up...e_mbpr_5Ghz.jpg 
MacBook Pro Retina 2013 3x3 5Ghz Link Speed to a 1x1 hAP AC Lite

As a rough guesstimate for actual speed, I like to use 60% which is already a very optimistic number for the speed that you may get. You may get higher speeds, probably not, but very easy to get lower speeds.   
1x1 - Link: 433Mbps - IRL: 260Mbps
2x2 - Link: 866Mbps - IRL: 520Mbps
3x3 - Link: 1299Mbps - IRL: 779Mbps
Other Factors
In real life (IRL), other things will affect the final speed that you get.
1. Distance
2. Line of sight
3. Door
4. Wall
5. Interference from neigbour's wifi

So many things, I'm just going to list 5.
WiFi speed tests
To give you an idea of the speeds, I did a few tests below.

The test is a 30 second iPerf3 TCP test. Data is sent from the server via the respective wifi router to the device.

The command for iperf3 where applicable. iPhones are using an app called WiFiPerf which is iPerf3 compatible.

*Note that these are tests of just the wifi. No internet involved. Get the wifi speed sorted out before worrying about the internet. So, again, this is all local area network,
**I'm lazy to edit it so if you see single chain, dual or triple chain, it means 1x1, 2x2 or 3x3 respectively.

Stuff Used
Server: Thinkcentre M73 - Ubuntu 18.04 LTS - iperf3 3.1.3
Laptop: MacBook Pro Retina 2013 - MacOS 10.13.6 - 2.4Ghz Dual Chain - 5Ghz Triple Chain - iperf 3.6
Phone: iPhone 6s - iOS 12.0 - Dual Chain - WiFiPerf 3.2
Network: Gigabit - Cabling: Cat5e
Distance: Approximately 4ft from device to wifi router.

WiFi Routers (to be tested)
1. Mikrotik hAP AC Lite - 2.4Ghz Dual Chain - 5Ghz Single Chain - AC750 (done)
2. Mikrotik hAP AC2 - 2.4Ghz Dual Chain - 5Ghz Dual Chain - AC1200
3. Mikrotik hAP AC - 2.4Ghz Triple Chain - 5Ghz Triple Chain - AC1750
4. Aztech FG7008GR - 2.4Ghz Triple Chain - 5Ghz Quad Chain - AC2400
5. D-Link DIR-878L - 2.4Ghz Quad Chain - 5Ghz Quad Chain - AC2600

Notes
• RouterOS 6.44beta6 (11/9/2018)
• hAP AC Lite: 3x100M ethernet bonding
  *because the hAP AC Lite only has 100Mbps network ports, I bonded 3 ports (300Mbps) to cater for WiFI AC speeds.
• The only tuning I did was lowering transmit power as I was only 4ft away from the wifi routers.
• WiFi chip features such as WMM, adaptive noise immunity, beam forming, or band steering are disabled.

Radio Environment
2.4Ghz Scanner and Frequency Usage
Tests were done in my house in the afternoon on a weekend. Typical double storey intermediate link house. Quite a few 2.4Ghz APs around but still can be considered good.
Since it's a weekend, more people are home and using their phones and laptops. It gets better in the afternoon on a weekday or in the early morning when everyone is asleep.
https://res.cloudinary.com/soonwai/image/up...Ghz_scanner.jpg https://res.cloudinary.com/soonwai/image/up..._4Ghz_Usage.jpg 

5Ghz Scanner and Frequency Usage
Very clean. There's only one 5Ghz AP and the signal is very weak.
https://res.cloudinary.com/soonwai/image/up...Ghz_scanner.jpg https://res.cloudinary.com/soonwai/image/up.../5Ghz_Usage.jpg 
Ethernet Speed Test (Control)

	Phone 6s	MBPR
Ethernet	94.41 Mbps	934 Mbps

Actually I forgot, I thought my iPhone Lightning-Ethernet was gigabit. It's only 100Mbps.

Mikrotik hAP AC Lite - 2.4Ghz Dual Chain - 5Ghz Single Chain - AC750

	iPhone 6s	link	MBPR	link
2.4Ghz Dual Chain (Early Morning)	91.57 Mbps	144 Mbps	-	-
2.4Ghz Dual Chain (Afternoon)	79.29 Mbps	144 Mbps	92.1 Mbps	144 Mbps
5Ghz Single Chain	240.53 Mbps	433 Mbps	244 Mbps	433 Mbps

hAP AC Lite only has 100Mbps ports so I bonded 3 ports to cater for WiFI AC speeds. I don't expect it to go above 300Mbps.


Mikrotik hAP AC2 - 2.4Ghz Dual Chain - 5Ghz Dual Chain - AC1200

	iPhone 6s	link	MBPR	link
2.4Ghz Dual Chain	-		-
5Ghz Dual Chain	340.88 Mbps	866 Mbps	357 Mbps	866 Mbps

Mikrotik hAP AC - 2.4Ghz Triple Chain - 5Ghz Triple Chain - AC1750

	iPhone 6s	link	MBPR	link
2.4Ghz Dual Chain	87.05 Mbps	144 Mbps	77 Mbps	144 Mbps
5Ghz Dual Chain	343.66 Mbps	780 Mbps	-	-
5Ghz Triple Chain	-	-	420 Mbps	950 Mbps

Aztech FG7008GR - 2.4Ghz Triple Chain - 5Ghz Quad Chain - AC2400

	iPhone 6s	link	MBPR	link	iPad 2017	link
2.4Ghz Dual Chain	-	-	-	-	-	-
5Ghz Dual Chain	304.96 Mbps	-	-	-	518.79 Mbps	-
5Ghz Triple Chain	-	-	875 Mbps	1300 Mbps	-	-

D-Link DIR-878L - 2.4Ghz Quad Chain - 5Ghz Quad Chain - AC2600

	iPhone 6s	MBPR
2.4Ghz Dual Chain	xxx	xxx
2.4Ghz Triple Chain	xxx	xxx
5Ghz Single Chain	xxx	xxx
5Ghz Triple Chain	xxx	xxx

bro... just want to ask. I'm a Maxis home wifi installer. but i do have doubts. im using huawei nova 4. occasionally i install 300mbps (300mbps DL and 50 UL) superfast package. sometimes i do get a speedtest of 190mbps for download and 45 for upload... sometimes 230mbps for download and 40++ for upload.. why is that? what affects this in my fon? and what spec in this fon that plays a part of this different speed test.. plsss guide me

Maybe a TV analogy is easier to understand.

The station broadcast in FullHD signal but your ancient TV can only receive normal signal. Even if the tower broadcast in 4K, your old TV won't see all the benefits. Same condition to your phone WiFi speed.

You need a better phone to reap the full benefit. Kinda surprised you guys are not trained on this considering how Maxis advertise their so-called Max-perts.

bro... just want to ask. I'm a Maxis home wifi installer. but i do have doubts. im using huawei nova 4. occasionally i install 300mbps (300mbps DL and 50 UL) superfast package. sometimes i do get a speedtest of 190mbps for download and 45 for upload... sometimes 230mbps for download and 40++ for upload.. why is that? what affects this in my fon? and what spec in this fon that plays a part of this different speed test.. plsss guide me

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 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), HTC Amaze 4G (2011). 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.

It's 2019 but so far no smartphone on earth comes with 3x3 MU-MIMO radio yet.

Thanks for sharing this info.... beneficial to me in my next purchase of smartphone

You're welcome. if you want a peace of mind just go for the flagship smartphones, you'll get the latest and greatest 2x2 MU-MIMO chip, it can't be wrong.

Something I'd like to point out though it's a shame that in year 2019 those smartphone vendors still didn't put 802.11ax chip into their flagship smartphones like the Huawei P30 series, Xiaomi Mi 9, Redmi K20 Pro, LG G8. So far only Samsung did it with their Samsung Galaxy S10 series. Then there's another smartphone vendor OnePlus famously known for their "flagship killer" slogan with flagship specs at an affordable price? Release their OnePlus 7 Pro in May 2019 after Samsung Galaxy S10 in February 2019 but still failed to put a 802.11ax chip into their smartphone. Yeah right "flagship killer" , maybe need to wait year 2020.

Added more information into my previous post.

2.4ghz can actually reach 130mbps with 2x2 devices provided no neighbour signals.

Need to know your home's layout & existing router location before further advise.

how to check if the device support this 2x2 40Mhz 802.11n aka dual band?

I got a tplink ac1200 using unifi. When I connect to wifi using s10 plus, there are couple of site that I cannot access and some games that load halfly. Anyone experience problem like that ?

Disable IPv6.