2.4 Ghz WiFi Download Speeds much slower than 5 Ghz and Uverse cap

srudenko

Reputable
Jun 6, 2015
9
0
4,510
Hello. I know my question has been asked before since I searched but there were no concrete answers so here is my question / situation...

I have AT&T Uverse 50 Mpbs down / 10 Mpbs up. House has 2 floors and I have 2 Asus RT-AC66U routers. One is in router mode and the other is the access point so this this way I have good coverage throughout the house.

Normally I don't perform speed test often and especially on WiFi but today I did and noticed that 2.4 ghz WiFi clients get download speeds of approximately 20 Mpbs which seems kind of slow. In comparison clients on 5 Ghz are getting over 50 Mbps.

I tried everything that I could think of which included the following:
-Unplugged / turned off all WiFi devices that I could find and think of
-Tried all sort of different WiFi options in the router..Auto, N only, different channel, 20 Mhz, 20/40 Mhz, etc...Made no difference
-Tried different laptops / phones - speed test was consistent on 2.4 ghz for all - around 20 Mbps
-Tried connecting to main router WiFi and then AP separately in case one of the routers is not working well - same result
-Both router and AP have latest firmware

Is this just how 2.4 Ghz network is and I should accept this or am I missing something and there is something else to check or try?

Right now I left the 2.4 WiFi settings like this:
AP: N Only / 20 Mhz / CH 1
Router: N Only / 20 Mhz / CH 11

Any advise, info or insight is greatly appreciated.

Thanks
 
Solution
If you have an android device, I would get WIFI Analyzer APP. It will show you all the WIFI signals around. It is quite possible that you just have too much 2.4Ghz congestion to get full bandwidth.

srudenko

Reputable
Jun 6, 2015
9
0
4,510


I used 2 laptops to test and both showed 72 Mbps link speed.

One was using an internal card, 2.4 ghz only. The other was using an AC Wi-Fi USB adapter.

Link speed on my LG V20 is 144 Mbps

Speed test on all when connected to 2.4 ghz is ~20 Mbps pretty consistently.
 

vmfantom

Notable
Nov 28, 2017
181
0
860


Like Bruce Hornsby said, that's just the way it is with 2.4 GHz. The RT-AC66U at 3-stream MIMO and 20 MHz would have a maximum Phy rate of either 195 or 216.7 Mbps. You have one RT-AC66U in AP mode, and since the same BCM4331 radios are being used on both to retransmit the 2.4 GHz packets, the throughput is cut in half. Now if you have need for a repeater setup in the first place, odds are that the modulation between the main router and AP mode router has probably fallen from 64-QAM to 16-QAM, so your Phy rate might be in the 117-130 Mbps range at best. CSMA/CA and QoS would bring the throughput down as low as 19.7 Mbps, so there you go. I'm not sure if disabling any QoS settings would shorten the backoff/contention windows, but in any case Asus' firmware doesn't let you adjust that stuff (and it may be hard coded in the Broadcom modules themselves).

Is MoCA or WoCA an option in your house?
 

kanewolf

Titan
Moderator
A host with a 144Mbit link speed should not have a 20Mbit limitation. Since you have hardware that is compatible, I would try running Merlin firmware on one of the units and see if that improves things. -- https://asuswrt.lostrealm.ca/ If it improves, then you could switch the other unit. If you don't like Merlin, you can switch back to Asus firmware.
 

srudenko

Reputable
Jun 6, 2015
9
0
4,510


Just to clarify - the AP is connected to the main router via Ethernet so its not a wireless repeater. If I am not mistaken it shouldn't cut the output in half with this setup.
 

vmfantom

Notable
Nov 28, 2017
181
0
860


In that case, you're right, the throughput wouldn't be halved. And there's no interference between the two routers on 2.4 GHz. Are the speed test results at 20 Mbps even when you're just an inch away from one of the router?
 

srudenko

Reputable
Jun 6, 2015
9
0
4,510


Yep, standing right in front of the router and testing with 3 different devices on Speedtest.net
Download results fluctuates and from test to test can be anywhere between 18 - 26 Mbps
Upload speed is always consistent around 12 Mbps
Same exact devices when connected to 5 Ghz on same network get around 50 Mbps or more in some cases on the download test.

I am thinking its just how 2.4 Ghz band is going to be. Neighbors, congestion, etc...
For now I will leave the firmware as-is since I see many similar posts / questions and people are using other routers, firmware, etc...with similar results.

The only reason why I started this speed test is because of Ring Video Doorbell :)
It's connected on the 2.4 ghz network (doesn't support 5 ghz) and is fairly close to the router. For the most part it works great but once in a while it produces just a black screen and no video. So their support suggested doing these speed tests by the router vs the door. I get similar speed at both places - I think that even 20 Mbps which is not full speed should be more than enough for that video cam.