Have I maxed out my Asus ac68u WiFi router?

KGB7

Very Senior Member
I’ve been using Asus AC68U ver1 for over a decade. For many years Ive used Merlin firmware.


Several dayago, I called Comcast/Xfinity. They were advertising new plans on their website. After a 15 min convo, long story short, I got an upgrade from 300Mbps to 800Mbps plan, and a $20/month discount for 2 years.

Earlier today, I have experimented for several hours, changing every setting in 5ghz band, including professional settings. I squeezed out everything out of the ac68u WiFi router.

I used; iPhone 14, Dell laptop with WiFi 6 card, apple laptop, and an iPad. I used Oocla speed test app on all devices. Tested speeds on 5-6 servers. Tested it and rested it a dozen times.

I was able to achieve up to 380Mbps, peak. But the average speeds is around 320Mbps on 5ghz band.

Part me of me was expecting a little bit more out of the ac68u WiFi router, but I’m guessing it’s time I need to upgrade.

Not looking for advice which router I should get, I’m simply sharing my experience. But if you want to share your experience, you are more welcome to do so.

My next WiFi router will be Asus. A WiFi router that has best WiFi speeds. I don’t play videos games and I don’t use QoS. I don’t need a long WiFi range or 10 core cpu.

I stopped using Diversion and Skynet. Instead I use AdGuard dns on the router. Diversion blocked Freevee movies and tv shows on Apple TV device and on my laptops ( Mac and Windows 10/11 ), so I I stopped using it.
 

ColinTaylor

Part of the Furniture
IIRC I was getting much more than that when I was using my RT-AC68U (but maybe I'm misremembering). Does this only effect WiFi devices, what about Ethernet connected devices?

Check the CPU load on the router when doing your speed tests. There are certain setup combinations where WiFi devices in particular become CPU limited.
 

Tech9

Part of the Furniture
On this router - possible only with TrendMicro components disabled and NAT acceleration enabled. Wired only, WiFi is still limited to about 500Mbps to 2-stream AC client.
 

Piotrek

Occasional Visitor
Did you check the connection speed after connecting the computer with the Ethernet cable to the router?
In the real world for Wi-Fi 5 (router or client AC), the connection speed is max. ~400~500 Mbps.
If you use a Wi-Fi 6 (AX) router you can increase the WiFi speed for your AX clients (eg. Dell laptop with WiFi 6 card).
 

RMinNJ

Senior Member
In my experience when I upgraded to 1 gig internet from 300 it showed many flaws in my setup. First the laptop I was using could not do the full 1000mbit wired..cpu and drivers etc could only do like 700 max.
Second I had a small gigabit switch that could not do the full 1000..even though it was a gigabit switch..it was good for like 600.
Third (well really the first thing i found)my router suddenly did not like the ethernet cable to the modem that been doing 300 fine.. this was only a 3 foot cable. Switched it to a cat 6a.
I'm sure wifi will always be slower sure but make sure you check your wired setup with better cables and a fast computer..
 

KGB7

Very Senior Member
Almost everything is disabled on the router, I’m not running any scripts, no QoS, no TrendMicro. CTF+FA is enabled. Via lan cable, I’m maxing out at 520Mbps, but that's because Im limited by the Cable modem. Currently using Asus CM-16 modem.

P.S.
CPU is usage during wifi speed tests, Core 1 - 60%, Core 2 - 40%
 
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L&LD

Part of the Furniture
Time to upgrade your router if you want to take advantage of the faster ISP speeds.

Either the RT-AX68U (good), RT-AX86U (better), or GT-AX6000 (best), should give you a significant performance boost to your network.

Your 9+-year-old router couldn't be prepared for what and how the devices, internet, and features have evolved over the last decade since it's been designed.

Even the current top AC class router (Asus, RT-AC86U) can't compare to current offerings. Note how one RT-AX68U in the link below entirely embarrasses 2x RT-AC86Us in AiMesh mode for one of my customers below.

Report - 2x RT-AX68U upgrade over 2x RT-AC86U in wireless backhaul mode


It's not just about CPU prowess either.

The RF design is greatly improved since 2013. For most/many of the newer routers, the RF has CPUs of its own. And the kernel, SDK, and other low-level factors all help to push the newest routers above the older units too.
 
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sfx2000

Part of the Furniture
I’ve been using Asus AC68U ver1 for over a decade. For many years Ive used Merlin firmware.

It's a 10 year old router, seriously - along with the Netgear R7000, Apple Airport Extreme 2012 - they were all best of class for 802.11ac Wave 1 - the 68u has benefited from long term support from Asus directly, and indirectly thru 3rd party support from @RMerlin and the scripting community here.

as good as it is... it is likely time to upgrade - better base support from Broadcom, Asus on the SoC - better firmware for the SoC and Wifi radios, and general overall performance.

this is about as close to a tribute I would do for the RT-AC68U - it was a great device, but time has certainly moved on...
 

KGB7

Very Senior Member
I was able to achieve over 560Mb/s via wifi. By downloading or by uploading large files to or from wired laptop.

But I can't come close to this speed when im downloading directly from Internet, even though im capped by the cable modem at 500Mb/s. I'll try a new modem tomorrow.
 
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andyross

Regular Contributor
The CM-16 modem is an ancient 16x4 DOCSIS 3.0 modem. It's about 600M theoretical max (38 x 16). What ISP do you have? For Gigabit, you probably need a DOCSIS 3.1 modem to properly get the speeds. I wouldn't use that CM-16 for anything over 200.
 

andyross

Regular Contributor
Just reread the original post. YES, you really need to update to DOCSIS 3.1 for (almost) Gigabit with Comcast. Plus, it's much kinder for your neighbors on the same node as you don't max out a bunch of D3.0 channels. The OFDM for D3.1 is MUCH more bandwidth available.
 

KGB7

Very Senior Member
Time to upgrade your router if you want to take advantage of the faster ISP speeds.

Either the RT-AX68U (good), RT-AX86U (better), or GT-AX6000 (best), should give you a significant performance boost to your network.

Your 9+-year-old router couldn't be prepared for what and how the devices, internet, and features have evolved over the last decade since it's been designed.

Even the current top AC class router (Asus, RT-AC86U) can't compare to current offerings. Note how one RT-AX68U in the link below entirely embarrasses 2x RT-AC86Us in AiMesh mode for one of my customers below.

Report - 2x RT-AX68U upgrade over 2x RT-AC86U in wireless backhaul mode


It's not just about CPU prowess either.

The RF design is greatly improved since 2013. For most/many of the newer routers, the RF has CPUs of its own. And the kernel, SDK, and other low-level factors all help to push the newest routers above the older units too.

What I can’t figure out, as to why I’m not getting 500Mbps speed on WiFi.
After extensive testing, moving large files on my home network, uploading and downloading, I was constantly getting an average of 560Mbps over WiFi.

I understand that my Asus cable modem is outdated, but I’m getting 500-520Mbps from it when directly connected to it via lan cable and same speed when I’m directly connected to Asus ac68 router via lan cable, while it’s connected via lan cable to Asus modem. So why I’m not able to get same speed via WiFi ( 500 Mbps )when I’m downloading large files from internet or while I’m performing speed tests?
CPU doesn’t get over tasked while I’m transferring files at 560Mbps via WiFi. Core 1 is around 65%, core 2 is around 45%.
 
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wouterv

Very Senior Member
450 Mbps is about the max I ever reached wireless with the RT-AC68U, but only under ideal circumstances (short distance and a laptop with a 2x2 AC adapter, 3x3 adapters are rare, with a 1x1 adapter you can expect 250 Mbps max).
See here: https://www.snbforums.com/threads/asus-rt-ac68u-firmware-version-3-0-0-4-384-45713.56052/post-483727
That time I had a 500 / 500 Mbps subscription.

Setting changes from factory defaults:
  • Advanced Settings - Wireless - Professional - 2.4 GHz:
    • Modulation Scheme: Up to MCS 7 (802.11n)
    • Airtime Fairness: Disable
    • Explicit Beamforming: Disable
    • Universal Beamforming: Disable
  • Advanced Settings - Wireless - Professional - 5 GHz:
    • Airtime Fairness: Disable
    • Universal Beamforming: Disable
 
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StrikerXXX

Occasional Visitor
I'm currently using the latest firmware available from asus for rt-ac68u v3. I tried using merlin but version 386.7_2 is causing problems here, losing ipv6 prefix for clients connected via lan port and 5ghz wifi disconnecting constantly.

In the official asuswrt these problems do not exist, sometimes there is a loss of ipv6 for the clients, but I just had to disable and re-enable the ipv6 option that normalized.

In the wireless option, I leave everything at the default, I just disable wps. In this configuration, I always get high speeds through wifi, at the moment the maximum I could get for 5ghz was ~320mbps in download and upload, I don't have other more modern equipment for testing, I use a redmi note 6 pro for testing, but I'm sure I can get speeds well above that.

I really wanted to continue using merlin, but 386.7_2 must have some incompatibility with rt-ac68u, I even thought about using the previous version, but I won't do that at this moment, it's easier for me to test the new version of fresh tomato that came out these days, it might even look better on this router.
 

wouterv

Very Senior Member
I assume all firmware for the RT-AC68U uses the latest and same Broadcom wireless drivers - 6.37.14.126 (r561982), that shall determine wireless performance from the router end.
At the client end there is wide variation of wireless chip sets and drivers possible.
It can be good to check if your computer has the latest driver for the wireless adapter, although some new drivers can be troublesome and an older driver can be better.
Specially some older Intel driver versions are known to be bad.

The RT-AC68U can deal with 3 data streams, called 3x3. To get the highest throughput the client shall also support 3x3.
Every 801.11ac data stream is good for a maximum data rate of 433.3 Mbps, two data streams sums up to 866.6 Mbps and 3 data streams up to 1299.9 Mbps.
The final throughput is in my experience maximum about half of the data rate, see my speedtest:

Dell Laptop showing as follows in the Client Status display:
1667736667997.png

Speedtest.net result at 5 GHz:
1667736708593.png

The laptop connects with two data streams and ~800 Mbps.
The speedtest throughput is about half of that with ~450 Mbps.
Downloads from a website do not always occur at the highest possible speed, it can be that the website limits the throughput to handle all the download requests (a server park also has a limit in their Internet connection).

The final and maybe most important factor are the physical locations and distance between router and client devices.
For sure it is the best to place the router in an open space, not hidden in a cabinet.
And the best wireless connection is the one with an open line of sight between the router and the client devices, not too far apart.
 
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L&LD

Part of the Furniture
What I can’t figure out, as to why I’m not getting 500Mbps speed on WiFi.
After extensive testing, moving large files on my home network, uploading and downloading, I was constantly getting an average of 560Mbps over WiFi.

I understand that my Asus cable modem is outdated, but I’m getting 500-520Mbps from it when directly connected to it via lan cable and same speed when I’m directly connected to Asus ac68 router via lan cable, while it’s connected via lan cable to Asus modem. So why I’m not able to get same speed via WiFi ( 500 Mbps )when I’m downloading large files from internet or while I’m performing speed tests?
CPU doesn’t get over tasked while I’m transferring files at 560Mbps via WiFi. Core 1 is around 65%, core 2 is around 45%.

There is not much to figure out here. Old tech is old tech, no matter what the theory may indicate.

Try one of the routers I recommended, you'll see an immediate jump in throughput and lower latency too on your network. The modem upgrade will only solve the size of your internet pipe, not your internal network's performance.
 

Tech9

Part of the Furniture
What I can’t figure out, as to why I’m not getting 500Mbps speed on WiFi.
After extensive testing, moving large files on my home network, uploading and downloading, I was constantly getting an average of 560Mbps over WiFi.

This router's radio BCM4360 doesn't have own processing unit and relies on the main CPU. When you transfer files LAN-WLAN there is no routing. WAN-WLAN traffic results in higher CPU load. What you observe on AC68U with 800/1000MHz CPU is less noticeable on AC1900P with 1400MHz CPU. I never had V4 in my hands for testing (1800MHz ARMv8 CPU), but I expect this h/w version will do 500+ Mbps on both LAN-WLAN and WAN-WLAN.
 

sfx2000

Part of the Furniture
This router's radio BCM4360 doesn't have own processing unit and relies on the main CPU

Not it doesn't - it does the AES encryption on chip, there's a Cortex-A series core on there just for that purpose - wl firmware has all the code to load up and run that processor.

It has to do the AES-CCMP acceleration for WiFi, and that offloads the host CPU - recall that 4360 is available not just for Router HDK's, but also for PC's...
 

Tech9

Part of the Furniture
Standard BCM4360 doesn't have CPU Offloading like newer radios, BCM4366 as an example. There is one only AC68U C1 revision with BCM43602 radio and own processing, but rare find. The difference in main CPU load is significant. I had RT-AC1900P and RT-AC5300 for direct comparison, with the same CPU BCM4709C0 ARMv7 1.4GHz. Different radios only result in 80% vs 20% main CPU load. BCM4360 may have something built-in, but still relies heavily on the main CPU. Perhaps in newer firmware versions, I don't know. This is what happens in real life use though.
 

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