Solved Slow WAN - Low CPU Usage (RT-AC66U B1 - AC68U_386.3_0 FW)

[Fiz]

I've noticed that my router(directly through the QOS Internet Speed test), and all attached gigabit LAN devices(through speedtest.net), experience much slower WAN speeds than the most recent official ASUS firmware for the router. I'm able easily saturate the router's gigabit WAN port, with the official firmware, at roughly 920 Mbps+ downstream. However, after immediately swapping back to the Merlin FW (RT-AC68U_386.3_0) my downstream slows to a much slower 200-300 Mbps.

The only helpful piece of information I've been able to glean so far is that CPU utilization during speed tests is much lower with the Merlin FW during speed tests. Particularly with the router's 2nd CPU core. The ASUS firmware appears to be utilizing more CPU power during these speed tests.

Is there a setting somewhere I need to change in the Merlin FW, or is this a bug? Let me know if more info is required, as I'd really like to be able to use the Merlin FW.

Router: RT-AC66U B1
ASUS Firmware: FW_RT_AC66U_B1_300438643129
Merlin Firmware: AC68U_386.3_0

Edit: LAN speeds do not appear to be affected

 

[ColinTaylor]

... my downstream slows to a much slower 200-300 Mbps.

This would be consistent with hardware acceleration being disabled. Check the status and reason at Tools - System Information > Network > HW acceleration

 

[Fiz]

This would be consistent with hardware acceleration being disabled. Check the status and reason at Tools - System Information > Network > HW acceleration

This appears to be the issue. I see this message: Disabled - incompatible with: IPTraffic

 

[Fiz]

Found and disabled it. Thank you Colin

Tools > Other Settings > Enable IPTraffic

Clearly I should have left that setting alone.

 

[MP35FJ]

Well with the latest ASUS and/or Merlin firmware 386.5, I am getting only 200-300 Mbps even with LAN switch control NAT acceleration set to CFT enabled (and I've tried spanning tree protocol on/off). The latest firmware no longer has the "Tools>OtherSettings" menu. And when I use an older version of the firmware, like 384.17, I am getting about 900 Mbps. Any ideas?

 

[ColinTaylor]

Well with the latest ASUS and/or Merlin firmware 386.5, I am getting only 200-300 Mbps even with LAN switch control NAT acceleration set to CFT enabled (and I've tried spanning tree protocol on/off). The latest firmware no longer has the "Tools>OtherSettings" menu. And when I use an older version of the firmware, like 384.17, I am getting about 900 Mbps. Any ideas?

Look at Tools > Sysinfo > HW acceleration. What does it say there?

 

[MP35FJ]

Enabled!

 

[ColinTaylor]

OK. How are you testing the speed? From a PC connected by Ethernet cable directly to the router?

What is your "WAN Connection Type" (under WAN - Internet Connection)?

 

[MP35FJ]

Yes, PC thru 1000 switch to router. Ansd as I said, I know the hardware is fine because earlier firmwares give me 900 mbps, which is what i get out of the router.

WAN type is Automatic ip

 

[MP35FJ]

900 mbps is what I get out of my modem - that's what I meant to say - so earlier firmwares have hardly any impact

 

[ColinTaylor]

Can you confirm that is problem is what we're assuming it is, that hardware acceleration is not working properly. To do that go to the Network Map page at look at the CPU usage. Now start downloading a large file or do a speed test in another browser. Does the CPU usage go up to 100%?

 

[MP35FJ]

With NAT acceleration on (LAN>SwitchControl), core 1 is about 60% and core 2 40% for a speedtest (results ~350 mbps). With acceleration off, the cores are at 97% and 60%, speedtest results are at 250 mbps.

 

[ColinTaylor]

With NAT acceleration on (LAN>SwitchControl), core 1 is about 60% and core 2 40% for a speedtest (results ~350 mbps). With acceleration off, the cores are at 97% and 60%, speedtest results are at 250 mbps.

Do you have AiProtection (or any of the other "Ai" options) enabled? If so turn them off and withdraw from the TrendMicro agreement at Administration > Privacy.

 

[MP35FJ]

No, none of those have ever been enables.

 

[degrub]

Do a factory reset, load latest merlin, reboot, manually configure minimum settings, reboot 3 times, what do you get ?

edit Just do the above per instructions here

L&LD

www.snbforums.com

@L&LD

 

[MP35FJ]

Well a nuclear reset did it - thanks