[RT-AC68U] Bug in Firmware: Lan speed slowdown!! Reproducible + Video!

[jobol]

Asus Firmware: 3.0.0.4.380_4164 and all other I tried
ASUSWRT-MERLIN: Firmware: 380.64 and all others I tried

Hey guys,

I am having an issue/bug with my RT-AC68U. The good thing is that I am able to reproduce it at will. The bad thing is that I can't find a fix for it.

I have an Internet connection of 150mbps, and that speed is guaranteed from my providers FTP server to me as obviously they can't guarantee it from other serves outside their network. And if I connect my computer straight to my router, I do get around 146mbps from their FTP server by downloading a 1GB test file. So far, so good.

I am connecting a PowerLine device to one of the AC68U ports, and on the other PowerLine end, my computer via the 10/100mbps interface on the PowerLink receiver (DHP-W310AV).

Now all is working fine and dandy except the following:

The speed of download I am getting from the internet after a factory reset of my RT-AC68U is 94Mbps which is great, and near the upper limit of the theoretical 100mbs interface on the PowerLink. *But * as soon as I reboot the RT-AC68U *without doing anything else*, the connection speed drops by half! and instead of the 94Mbps, I get around 52Mbps!!!!

This is without me changing anything at all beside rebooting! If I reboot again, same deal, I get the same diminished speed on the LAN port, no matter how many times I reboot.

Now...

If at any time, I do a Factory Reset *without doing anything else*, after the RT-AC68U has finished rebooting, I am back to the 94Mbps speed, and the speed is kept, until the first time the router is rebooted. Once it is rebooted, the speed is cut in half and I am back to 52Mbps!!!

I get the exact same bug with AsusWRT-Merlin as well!

Any help would be appreciated!

Edit: Video removed because no longer needed.

 

[eddiez]

Do you have QoS active on the router?

 

[jobol]

Do you have QoS active on the router?

No, nothing at all.

If you notice in the video, I do a factory reset, and the QOS is disabled by default.

I *never* change any value after the factory reset, I only reboot the RT-AC68U *not changing anything else*, and my LAN speed is cut in half!!

Resetting to factory defaults brings the LAN to full speed again and it is maintained as long as the router is not reset nor powered down... and rebooting the router halves the LAN speed, until I do a factory reset.

The same PowerLink unit, doing the *exact* same test, downloads at full speed (94mbps) using a ZyXEL router, and rebooting that router n times have absolutely no effect on the link speed, as it should be.

It is a bug within the RT-AC68U and AsusWRT-Merlin firmware.

 

[hggomes]

Check WAN/LAN link speed under TOOLS, then reboot and compare them.

 

[jobol]

Check WAN/LAN link speed under TOOLS, then reboot and compare them.

After restore factory default:

100Mps Full Duplex

After restart:

100Mbps Full Duplex


So it must be something else.

On another note, I did the following test. I restored factory defaults, and rebooted, and before I log in to the interface, I rebooted via the power ON/OFF switch a couple of times, and then I connected the PowerLine device. And low and behold, I got full speed. But as soon as I ran the setup wizard, and rebooted, the speed dropped to 50% again!!

So the setup wizard or the first run of the GUI interface must be overriding something in the factory config that is causing the 50% LAN slowdown on the PowerLine!!

Is there any way to dump the configuration (in a human readable format preferably) immediately post factory restore, and then run the setup wizard, dump it again, and do a comparison?

 

[jobol]

Update:

I found the culprit:

After factory restore:

After reboot:

The Hardware Acceleration Enabled went from CTF to CTF + FA by itself after the initial restart!!!

So my guess is that the PowerLine adapter is not liking the Hardware Acceleration Enabled (CTF + FA)

I tested with Hardware Acceleration Disabled and got back my 100% LAN speed, but at the expense of 60% CPU load on the Core1!!!

Is there a way to manually enable Hardware Acceleration Enabled (CTF) only as per the post Factory Restore, witout the FA?

Or even better, a way to have a Per LAN Port or per MAC address a "CTF" or "CTF + FA" configuration? Like this I can only set it or disable it for the PowerLink device without penalizing the rest of the devices connected to the LAN.


Thanks.

 

[FTC]

Hi, I think that many options in the router do prevent FA from enabling, such as enabling traffic statistics, QoS, and many more.. you could try to enable any of these functions and theoretically FA would not even be attempted. In my case (RT-AC3200) I have not even found out what to deactivate to get FA...

 

[jobol]

Hi, I think that many options in the router do prevent FA from enabling, such as enabling traffic statistics, QoS, and many more.. you could try to enable any of these functions and theoretically FA would not even be attempted. In my case (RT-AC3200) I have not even found out what to deactivate to get FA...

Yeah, but I do not need any of these functions, and they will end up taking CPU resources unnecessarily...which is what I a trying to prevent in the first place.



.

 

[hggomes]

Compile it without FA support, you can also try to connect directly and see the results first (without PL adapter) .

 

[Grandpa Simpson]

When your next drop hits, and my guess is it will.
Well depends upon if your using Windows 10, if you are then my guess is your next whine will be in a couple of hours.
ill then tell you how to fix it,
I tried all the same steps you did and found out culprit was not Router, but the OS making my Router F.U.B.A.R
If you do not reply later with a post about new drops, then i hate your guts nah all love m8.
Best of luck fingers crossed, when i tried the restore on Router it took MS 3 hours before showing a Red Wood up my tail gate and saying.
We will make a update to update the update which is giving another update problems their by shutting Router almost off by blocking it.

 

[FTC]

Yeah, but I do not need any of these functions, and they will end up taking CPU resources unnecessarily...which is what I a trying to prevent in the first place.
.

Well, of course I was only talking about a bypass for a found defect. In a sense you are already attempting a bypass since CTF should be slower and more CPU taxing than CTF+FA already and not the opposite...

 

[RMerlin]

Last I checked, having STP enabled on the LAN -> Switch Control page would cause FA to be disabled . But since Asus changed the FA compatibility rules a number of times, I don't know if that's still the case.

 

[john9527]

Sounds like your powerline adapters may be having a problem with FA mode (not a defect per se). You can try this....

nvram set ctf_fa_cap=0
nvram commit

and reboot. This may prevent fa mode being activated.

 

[jobol]

Sounds like your powerline adapters may be having a problem with FA mode (not a defect per se). You can try this....

nvram set ctf_fa_cap=0
nvram commit

and reboot. This may prevent fa mode being activated.

That worked, although the interface now says "Enabled" without any specific details:

 

[doczenith1]

I also am seeing an issue with CTF+FA on 380.64 on my 68U. After installing the firmware and doing a reset to defaults I did a very minimal setup. As previously stated only CTF was enabled until I did a reboot at which time CTF+FA was enabled. When running a speedtest the test takes longer to start and I'm getting around 750/280 down/up. If I enable Traffic Analyzer - Statistic and then reboot I'm back at only CTF. The speedtest runs normally and I'm back to my normal 940/940 with 100% cpu 1 usage. With stock ASUS firmware and CTF+FA enabled I get 940/940 with negligible cpu usage.

So it looks like 380.64 doesn't like CTF+FA on the 68U.

Edit: Appears to only be an issue with the Ookla speedtest (firefox and edge). The xfinity flash based test runs fine and the DSLReports HTML5 test run fine.

 

[jobol]

I also am seeing an issue with CTF+FA on 380.64 on my 68U. After installing the firmware and doing a reset to defaults I did a very minimal setup. As previously stated only CTF was enabled until I did a reboot at which time CTF+FA was enabled. When running a speedtest the test takes longer to start and I'm getting around 750/280 down/up. If I enable Traffic Analyzer - Statistic and then reboot I'm back at only CTF. The speedtest runs normally and I'm back to my normal 940/940 with 100% cpu 1 usage. With stock ASUS firmware and CTF+FA enabled I get 940/940 with negligible cpu usage.

So it looks like 380.64 doesn't like CTF+FA on the 68U.

How do you know the HW Acceleration state with the Asus firmware?

 

[doczenith1]

How do you know what state is the HW Acceleration in with the Asus firmware?

On the LAN>Switch Control tab it will show NAT acceleration on auto and then to the right will list whether only CTF is enabled or CTF + FA is enabled. This also works on Merlin's firmware.

How are you testing your speeds? I just found out that only the Ookla test is having issues. The DSLReports and xfinity test work fine with CTF + FA enabled.

 

[jobol]

On the LAN>Switch Control tab it will show NAT acceleration on auto and then to the right will list whether only CTF is enabled or CTF + FA is enabled. This also works on Merlin's firmware.

How are you testing your speeds? I just found out that only the Ookla test is having issues. The DSLReports and xfinity test work fine with CTF + FA enabled.

My issue is definitely NOT the speed test's fault. It is the PowerLine adapter that is somewhat slowed down by the FA.

As soon as I disable the FA, I get back at full speed on the PowerLine link.

Weirdest part is that I have a hardware revision A2, and thus, should not have Hardware accelerated FA to begin with.

 

[jeff3820]

On the LAN>Switch Control tab it will show NAT acceleration on auto and then to the right will list whether only CTF is enabled or CTF + FA is enabled. This also works on Merlin's firmware.

How are you testing your speeds? I just found out that only the Ookla test is having issues. The DSLReports and xfinity test work fine with CTF + FA enabled.

I am also seeing some weirdness with hardware acceleration. I also have gigabit Ethernet and when CTF and FA are active I also see inaccurate and erratic measurements by the Ookla Speedtests (146 up and down), some slowdowns with DDNS remote access, and other occasional slowdowns when loading web pages. As mentioned, the Xfinity and HTML5 tests (DSLReports are fine). I turned on Traffic Analyzer statistics and rebooted. This eliminates FA and only CTS is active. When running Oolka speedtests again I see the expected speeds...about 850 down and 385 up. Other page loading weirdness disappear as well. With stock firmware (3831 I believe) I used to see 940/385. Hence there is some weirdness with the Flow Accelerator in the current Merlin releases. This is reproducible.

 

[sfx2000]

Last I checked, having STP enabled on the LAN -> Switch Control page would cause FA to be disabled . But since Asus changed the FA compatibility rules a number of times, I don't know if that's still the case.

Just an FYI...

STP on a home LAN is a bit unusual - but some services will drive things - most recent DirecTV boxes, in a flat LAN config, will push a lot of STP traffic if attached - it's because of their MOCA bridge if DECA's are in place...