Max wireless throughput on RT-AC1900P

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Vishnu Rao

Regular Contributor
I have a RT-AC1900P running Merlin firmward. It works great. Super stable. But I am not quite happy with the wireless throughput. On wireless data throughput between my devices and wired NAS is only 20-25 MBps. But if throughput to my NAS from a laptop wired to the router, I can easily hit 114-116 MBps read from the NAS and 65-70 MBps write.

My family now shoots 4K videos on our phones. Viewing these videos after dumping them on the NAS has become a hassle, as there is buffering and stuttering in the videos being streamed.

What is the throughput measured by other folks in this forum? Are there any specific settings for improved throughput?
 

Tech9

Part of the Furniture
Common clients are 2-stream. Close to the router the maximum link speed is 866Mbps. Approximately 1/2 is the throughput, in realistic Wi-Fi environments. Up to 480Mbps translates into up to 60MB/sec. This is the maximum you can get. AC1900P wireless can go faster, but to rare 3-stream client. Further away from the router the speed will drop. Replacing the router and using the same clients may not improve the speed. You will have speed increase only if your clients support AX and you replace the router with AX capable.

4K compressed video stream is about 40Mbps or 5MB/sec. AC1900P can definitely do that. Are you sure there is no other issues with your network?
 

Vishnu Rao

Regular Contributor
Thanks for your response. I understand that theoretical speeds may not be achieved, but I was surprised by the difference between theoretical and actual, even when the laptop was right next to the router. If I could achieve even half of the theoretical max, I would be happy. :)

I have a USB-AC88 dongle which is meant to provide best compatibility with the ASUS router. The 20-25 quoted in my original post was with this adapter. The reason I need faster speed is to reduce time to copy over large videos from the 3 phones in the home.


With respect to the buffering, I think I found the problem. I was trying to stream to a RPi 3 Model B which only supports "b/g/n single band 2.4 GHz" as per Wikipedia. Also I don't know if the device supports downscaling of 4k videos to 1080p.

A friend suggested that having two network names for 5Ghz and 2.4 Ghz devices helps. I have created two network names and anything that is bandwidth sensitive gets on the 5Ghz. After making this change, the speeds seem to have gone up by about 3-5 MBps. I will take any improvements.

No plan to upgrade to AX at this time as none of my devices supports AX.
 

Tech9

Part of the Furniture
Some laptops have 1-stream clients, limited to 433Mbps link speeds, or about 200Mbps throughput, or about 25MB/sec. There is a possibility the client is the bottleneck. Your USB adapter has 3x3 radio up to 1300Mbps link speeds on AC, but two factors may limit the performance - the distance from the router and the USB port it is plugged in. Greater distance (or obstacles) reduces the maximum possible speeds. Some USB ports fall back to USB 2.0 and also limit the speed. You have to check before you make decisions. I believe, your AC1900P router is capable enough to do what you need. I don't use Asus routers in my home setup, but I have one AC1900P in my collection and I know what it is. It's the fastest 1.4GHz CPU variant of the very reliable and still popular AC68U.

Separate 2.4GHz and 5GHz SSID help locking fast devices to the faster 5GHz band. Your router doesn't support SmartConnect anyway and where the devices will connect is unpredictable. Devices sticking to the 2.4GHz band will have limited throughput. Your friend's suggestion is correct.
 

Vishnu Rao

Regular Contributor
The primary reason I doubted the router is because multiple devices on the network like an iphone XR, OnePlus 7Pro, Essential PH1 all register about 20-25 MBps when copying over videos. And the USB-AC68 registers similar numbers.

One thing to note is that switching to separate SSID did not enable any throughput improvement on any of the phones.

As you noted, for now the RT-AC1900P works great for my needs. The signal is great as the router is mounted high up with no interference to most high bandwidth needing devices.

My laptop's USB port is definitely USB 3.1. So I doubt its the laptop's USB port limitation. Also note that I disabled laptop's built in wifi, plugged in the USB-AC68 and placed the laptop right next to the router. So distance is not a factor.

Maybe interference? I doubt, since I live in a single family home with closest neighbor's home atleast 30ft away. The wireless site survey does indicate multiple networks in the vicinity, but my control channels are unique from the list that shows up in the survey.
 

Tech9

Part of the Furniture
Maybe interference?

Try the standard 36-48 and 149-161 range channels, even if you see networks around on the same channels. What's important is available throughput, not how many networks operate on the same channels. For me, lower channels provide higher bandwidth than higher. Everyone's Wi-Fi environment is different. You have to experiment. Post a screen shot of your Wi-Fi settings, something may be wrong there. I did test AC1900P from 2-stream AC laptop to my wired NAS and got up to 52MB/sec speeds. Laptop to another wireless client is indeed 1/2, the router's radio has to do 2x work.
 
Last edited:

Vishnu Rao

Regular Contributor
I think my clients are probably not capable of pushing high bandwidth. I tried with more clients and on my work laptop the throughput is significantly better. It has a Intel dual band wireless chipset as noted below from Windows 10 wireless settings page:

Protocol: Wi-Fi 5 (802.11ac)
Security type: WPA2-Personal
Network band: 5 GHz
Network channel: 157
Manufacturer: Intel Corporation
Description: Intel(R) Dual Band Wireless-AC 8265
Driver version: 20.70.19.1

This was able to hit average 60 MBps with no other changes besides splitting the 5Ghz to a separate SSID name.

But it still beats me why the USB-AC68 was getting lower throughput. On the product page they claim a bandwidth of 1900 MBps. Even a quarter of that would be great.
 

Tech9

Part of the Furniture
On the product page they claim a bandwidth of 1900 MBps

Marketing. Mbps, not MBps. The sum of maximum link speeds 600+1300 on 2.4GHz/5GHz. This adapter should be able to do 1300Mbps link speed in close proximity to the router though, or >80MB/sec. If you see constant 20-25MB/sec, this perhaps indicates USB 2.0 connection. Try forcing USB 3.0 only in drivers or change/update the drivers. This adapter is Realtek RTL8814AU chipset based, re-branded Edimax device. I had some issues with similar chipset devices, constantly falling back to USB 2.0 speed. You can try with the chipset driver from Realtek:
 

Vishnu Rao

Regular Contributor
Sorry for the delay in getting back. Once its Monday its back to the grind!

yeah. Its Mbps. Good catch.

With the adapter connected to windows 10 or Ubuntu 20.04, they both report as 1.3 Gbps link speed in close proximity and also at some distance (with line of sight to the router and no obstructions)

I am begining to suspsect its the fallback to USB 2.0 issue. I will try to update the driveer. But the version number of the driver feels strangely familiar. I recall seeing similar or if not the same version number in windows 10 with the USB-AC68 adapater plugged in. I will double confirm later today.

1634769574386.png
 

Vishnu Rao

Regular Contributor
Here is the info with the USB-AC68 plugged in

Protocol: Wi-Fi 5 (802.11ac)
Security type: WPA2-Personal
Network band: 5 GHz
Network channel: 157
Manufacturer: Realtek Semiconductor Corp.
Description: ASUS USB-AC68 USB Wireless adapter
Driver version: 1030.27.425.2018

Crudely interpreting the version numbers, since the driver version ends in 2018, I think the driver installed on my system i.e. the windows inbox driver maybe newer than whats on the realtek's website. Do you still recommend I try the one from realtek's website?

Another question, how do I force USB 3.0 mode in the driver settings?
 

Tech9

Part of the Furniture
I don't have any similar USB adapters anymore, but I remember in driver settings there was something called USB SF Mode or USB Switch Mode. About drivers - you have to experiment. I don't know which one works better.
 

Vishnu Rao

Regular Contributor
USB SF Mode is one of the options available, but changing it did not make a difference. Other option was USB RF SELECT. That did not make a difference.

1635039494909.png



At this point I am ready to give up. Improvement in throughput is not a must have for me. More like a nice to have. So I am going to pause on this for the moment.
 

Roy360360

Occasional Visitor
USB SF Mode is one of the options available, but changing it did not make a difference. Other option was USB RF SELECT. That did not make a difference.

View attachment 36976


At this point I am ready to give up. Improvement in throughput is not a must have for me. More like a nice to have. So I am going to pause on this for the moment.
I don't know if this was tried, but have you set the channel width to 80Mhz on your router?

I just tried copying a file off my NAS on my laptop 2x2 AC laptop from my AC1900.

I'm getting ~50-55MBps. This through a few walls and one floor. With wired I get around 100-109MBps
 

dlandiss

Very Senior Member
What is the throughput measured by other folks in this forum?
My downstairs access point is an RT-AC68U. Connected to it on 2.4GHz Ch11 my mobile phone shows 80Mbps download.
 

Vishnu Rao

Regular Contributor
I don't know if this was tried, but have you set the channel width to 80Mhz on your router?

I just tried copying a file off my NAS on my laptop 2x2 AC laptop from my AC1900.

I'm getting ~50-55MBps. This through a few walls and one floor. With wired I get around 100-109MBps


I am already using 80Mhz.

1635555001867.png


I have tried all other options like the 20/40/80 and 20, 40, 80. One of the options did reduce the throughput slightly, but none of the options could produce the kind of throughput you are seeing.
 

Tech9

Part of the Furniture
@Roy360360 transfer speed is similar to the speed in my test. I used Ch.40, 80MHz. PMF, Airtime Fairness, Universal Beamforming disabled. Distance to the router about 4m, the same room. 420Mbps or 52MB/sec to HP laptop with factory RTL8822CE Wi-Fi, 2x2 AC.
 

Roy360360

Occasional Visitor
I am already using 80Mhz.

View attachment 37083

I have tried all other options like the 20/40/80 and 20, 40, 80. One of the options did reduce the throughput slightly, but none of the options could produce the kind of throughput you are seeing.
What's your laptop getting for link speed?


1635566834552.png

Check right by your router if you can. That might give us an idea of why your transfers are so slow.

Swtiching between 20/40/80 should make significant differences in performance.
 

Vishnu Rao

Regular Contributor
All,

To ensure I reduce variables, I reset my router and network settings on my windows10 laptop. After this reset, I setup 2 wifi networks on the RT-AC1900P. I retested with the two wifi adapters as below:

1.
Manufacturer: Intel Corporation
Description: Intel(R) Dual Band Wireless-AC 8265
Driver version: 20.70.19.1

Achieved about 70 MBps read from the wired NAS.

Status:
1635712748159.png


2.
Manufacturer: Realtek Semiconductor Corp.
Description: ASUS USB-AC68 USB Wireless adapter
Driver version: 1030.27.425.2018

Achieve about 30 MBps read from the wired NAS

Status:
1635712579136.png


So it does not appear to be an issue with the router, but with the USB-AC68 adapter.

I had bought this used on Amazon a few years ago. Maybe I got a defective one?
 

Tech9

Part of the Furniture
I still believe it uses USB 2.0 and limits the transfer speed. Have you tried plugging it on another PC?
 

Vishnu Rao

Regular Contributor
Yeh. By defective, I meant that its defective that it always goes to USB 2.0 and is unable to support USB 3.0.

I have tried plugging into the original desktop that it used to be connected to. But then that desktop is about 40 ft away, but with straight line of sight to the router. I am unable to move the desktop closer to the router. But numbers from that desktop with the adapter connected to an USB 3.0 slot is definitely <30 MBps.

I just bought a laptop for a friend of mine. It should arrive in a few days. It has a USB 3.0 slot as well. Laptop spec here: https://support.hp.com/us-en/document/c07224652


So I will update this tread based on testing on the new laptop later this week.
 

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