Low 802.11AC connection speeds

ep3w

Gawd
Joined
Apr 4, 2008
Messages
646
I just upgraded my home network to an Edgerouter X and a Unifi UAP-AC-PRO. My main goal was to increase reliability and also to upgrade to AC for the increased speed in local file transfers.

I setup the UAP-AC-PRO and tested everything in a before and after situation and everything was as expected. I have two desktops using the TP-LINK TL-WDN4800 which have the Atheros AR938x chipset capable of 450Mbps. On both machines I could connect to the UAP at 450 Mbps rock solid.

Now to take advantage to the 802.11AC I just upgraded one machine to the TP-LINK Archer T9E which is capable of 1300 mbps (same as the UAP-AC-PRO) on 5ghz. However I only seem to be able to connect at about 525-585 Mbps (according to the windows utility). The radios in the UAP are set to high power and 80hz, I haven't configured much else. Any suggestions here on how to get it connecting higher? I feel like I am missing something. I'm probably only 20', 2 walls and 1 floor above the UAP.

At 40hz I'm only able to connect at 270-325 Mbps. I would think I should get at least 450 Mbps like the last adapter.
 

FnordMan

[H]ard|Gawd
Joined
Apr 22, 2011
Messages
1,727
Is there a wall or almost anything at all between you and the AP? The quoted numbers are basically only applicable inside a faraday cage with no other devices operating. In the "real world" your speed will vary a *lot* depending on a lot of factors.

realistically given we're talking about desktops here the best solution would be ye olde ethernet cable.
 

Raekwon

[H]ard|Gawd
Joined
Nov 29, 2001
Messages
2,010
What speed are you getting when you are close to the AP, with no obstructions between you and AP?
 

rma

Limp Gawd
Joined
Mar 16, 2015
Messages
200
Try doing a WIFI scan of the used WIFI channel, to see if you got some sort of interference from other channels that my be ruing your reception.
 

Grentz

Fully [H]
Joined
May 5, 2006
Messages
17,159
As said, it is definitely a theoretical max speed when it comes to wireless. You very very rarely will see the full 1300 on the windows utility.

That said, if you want to see the best, check for interference (you can even use the new AC PRO's scan feature via the controller) and then make sure you are literally within a few feet of each other for the devices (no obstructions either).

I have two of the AC PROs in my house and with my Macbook Pro it will very between 300-400 and 800-1000 depending on conditions.
 

stevewm

2[H]4U
Joined
Jul 18, 2001
Messages
2,277
5Ghz wireless is attenuated a LOT more than 2.4Ghz. It will not go nearly as far if there are walls in between you and the AP. Depending on the material your walls are made from, the attenuation can be substantial.

What are your actual tested throughput numbers? The connection speed numbers as shown in Windows only state the maximum possible at that given point, not the actual speed. Another thing to remember is that these numbers are the "full duplex" i.e. a sum of the total in both directions at the same time. Wireless is a half duplex medium, only one side can talk at a time, so your actual tested throughput in any given direction will be slightly less than half of this number.
 

Mackintire

2[H]4U
Joined
Jun 28, 2004
Messages
2,902
The unifi APs are like semi-trucks designed to handle heavy loads with 20-60 users. They are slower than most consumer grade APs, but unlike a consumer grade AP that will roll over when you have more than 15 users, the UNIFI just works.

Now that I've said that, there is an update that is expected later this year that will change the QOS airtime balancing engine to be biased towards performance for (few) users.

When released expect a 25-30% peak thoughput increase. I'm pulling these numbers from forum comments and have no direct experience with the "currently alpha" firmware.
 

bman212121

[H]ard|Gawd
Joined
Aug 18, 2011
Messages
1,675
There is a lot going on with your sentence that I'm trying to simply:

You have client A and Client B, both with TP-LINK TL-WDN4800 card in it. Using those cards with your AP positioned in one location, both of them are able to get 450Mbps using 5ghz and HT40 on N to the UAC-AP-PRO?

Now with everything the same you simply upgraded Client B from a TP-LINK TL-WDN4800 to a TP-LINK Archer T9E and in the exact same setup as before, just with 5ghz AC and 80mhz channels now you're getting slower speeds?

If I read through it correctly, it would seem as though your new card doesn't have as strong of a signal that your old card did. Wifi performance is largely dependent upon the signal to noise ratio that is it able to achieve. In order to go from N to AC, you have to have a stronger (Cleaner) signal than previously in order to take advantage of the increased speeds. On the back end the difference is between whether or not you can go from 64 QAM to 256 QAM and still keep the same encoding rate. It sounds like you signal strength likely went down instead of up with the new card. But in order to really take advantage of AC you might also need to move the AP closer still if you want to increase speeds.

I'll say this again though too, if you want speeds to increase, the signal strength (quality) has to go up as well. It WILL take a stronger signal to get AC 1300Mbps than it does to get N 450Mbps. Sometimes you'll be lucky enough that your signal was already strong enough to support higher speeds. Other times if your signal is already marginal, simply moving to a newer AP with faster speeds will not be any faster because the signal strength isn't there. That's something that none of the manufacturer's are going to tell you, but it's a huge point to note.



For anyone curious here is a slightly deeper explanation.

AC1900 First Look: NETGEAR R7000 & ASUS RT-AC68U - SmallNetBuilder

A quick look at his test charts will give you a great example. You can see that on this page a 2.4ghz link is able to hold around the same speed all the way out to 36dB of attenuation. So it doesn't matter if you had 100% signal or like 50% signal, there is plenty of overhead so you'll end up with the same speeds in multiple locations. Now flip over to the 5ghz chart on the next page. Faster speeds are present because of the additional encoding rates, (In this case it's N vs AC) but you can also see how much faster things fall off. There isn't nearly as much overhead with these and by the time you hit 36dB of attenuation, the speeds are almost the same as they were in the 2.4ghz band. It has nothing to do with the band itself, it's simply the encoding used to transmit the data with. If you look at an AC wiki: IEEE 802.11ac - Wikipedia, the free encyclopedia You'll see that 1300Mbps AC is MCS9 where 450Mbps in AC is MCS7. Now look at the N chart: IEEE 802.11n-2009 - Wikipedia, the free encyclopedia MCS7 is identical to MCS7 in AC. It's the same encoding. AC just added two additional speeds above what N can handle, but they require stronger signals to use. The highest MCS is only achieved with the strongest signal (Not signal power, but signal to noise, you can have a lower signal output and still have faster speeds if the amount of noise is lower) and your device will automatically start going down the chart until it finds a speed at which it can use (From the highest number to the lowest number). If you go back to those router charts, that's exactly what happens as the attenuation increases. So the reason why it's the same should be no surprise, they will both end up on the same encoding rate at a certain level of signal. Once you get to the highest MCS level you can't go any faster. N appears to hit it's fastest speed around 36dB in those charts, but AC with two additional rates needs to get down to 18dB of attenuation (or less) in order to fully use them.
 

Vengance_01

Supreme [H]ardness
Joined
Dec 23, 2001
Messages
6,212
Also note if you look for info on Unifi UAP-AC-PRO AP's there are alot of people who have similar issues. Their AC gear is just not fully baked yet. I look to see if there is new firmware etc..
 

w1retap

[H]F Junkie
Joined
Jul 17, 2006
Messages
12,335
Yup.. I bought (3) UAP-AC-PRO's to outfit my home.. then it seemed their firmware was just not up to par. They would have issues pairing, get terrible speed more than 10 feet away or through a wall, and randomly disconnect/reconnect to the UniFi gateway. I ended up selling them after 2 weeks of troubleshooting with Ubiquiti support and their forums. I went with (3) Asus RP-AC68U's and couldn't be happier.
 

Gomar

Limp Gawd
Joined
Oct 25, 2007
Messages
289
At 40hz I'm only able to connect at 270-325 Mbps. I would think I should get at least 450 Mbps like the last adapter.

OMG, I guess some people are just not satisfied no matter what they've got.
Keep in mind, it's all relative; I get 25mbps and sometimes more. I've just downloaded a 350mb movie in some 10 secs. Such speeds were unimaginable in the 1990's with 56kb modems.
 
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