RT-N66U WAN bandwidth?

[Sanya IV Litvyak]

Hi,

Let me just begin by saying that I'm not sure that this thread is in the right board, I hope it is.

So to the problem, "I" recently upgraded my network from 100/10 to 500/50 and with that upgrade I got a new cable modem. Just by plugging my computer into the new modem and running a speed test I get the advertised speed of 500/50 (roughly, measured in Mb/s) but when I try through the Asus router (Modem in bridge mode) I get around 230-260 Mb/s down and 50 Mb/s up and looking at that download it's almost half of what I should be getting.

I'm using Asuswrt-merlin version 378.53

When looking at the routers network map page I can see that the CPUs Core 1 is using ~99% when downloading in ~250 Mb/s .. So am I right in assuming that this is a CPU bottleneck issue? And beyond that, what is the point of Gb/s Ethernet ports if they can't be used with those speeds because of CPU restraints? (if that is the case) =/

Is there any kind of optimization I can do in the settings to make it work better?

I do have DNSCrypt set up in the router.

(Using Cat 5e and Cat 6 cables)

Regards,
Sanya IV Litvyak

 

[Slamb]

i dont think its a cpu issue, my slower rt-n56u is working well even at 1 Gb/s speed
did u try factory reset?

 

[Billy Jean]

Exact same issue here, just got ATT Gigapower (1Gbps) i have an AC66U and am only getting around 200mbps down and around 800mbps up when on the ASUS Lan. If i plug directly into the ATT Router i get around 900mbps up/down. I have reset the Asus, tried multiple firmware versions, nothing worked. the CPU does peg out when running a speed test, i have verified hardware acceleration is enabled.

 

[Sanya IV Litvyak]

i dont think its a cpu issue, my slower rt-n56u is working well even at 1 Gb/s speed
did u try factory reset?

I have not tried a factory reset and I'd rather not considering the difficulty I had setting up DNSCrypt properly, it would probably take me a whole day just to set everything up again. =/

Edit: Is it possible that the Asus Router and the modem negotiate the wrong speeds on the link between them? I remember that being a thing when configuring Cisco routers but figured these home routers would just set up the highest possible? If the wrong speeds are negotiated, is it possible to re-negotiate another speed manually?

 

[Slamb]

you can save your settings to a config file and after reset upload it through the same interface page

 

[Sanya IV Litvyak]

you can save your settings to a config file and after reset upload it through the same interface page

I'd still lose the DNSCrypt installation as well as its configuration as well as the one file (Which I can't remember which it is) I had to modify to fix the system time on the router (Otherwise at reboot the time would be way off)

 

[Zirescu]

You could use John's NVRAM tool to do the config backup which also takes a backup of the jffs. Do your test without restoring things to see if you get the speeds you're looking for and then restore to see if you still keep your speeds.

 

[wayner]

The same issue is mentioned here: http://www.snbforums.com/threads/rt...expected-on-high-speed-fibre-connection.9425/
and here http://www.snbforums.com/threads/hw-acceleration-on-rt-n66u.9888/
and here http://www.snbforums.com/threads/does-merlin-have-trouble-with-fast-internet-connections.23216/
so I don't think it is a settings issue.

It seems that using certain functions cause HW acceleration to shut off and without HW acceleration this router seems to be limited to a WAN speed of about 230 Mbps. Now that more and more people are getting internet connections faster than 250 Mbps they are starting to notice this.

 

[wayner]

And beyond that, what is the point of Gb/s Ethernet ports if they can't be used with those speeds because of CPU restraints?

Well, Gb Ethernet ports are useful to allow LAN-LAN connections of 1Gbps. Don't forget that this router, like most home routers, is also a four port switch.

 

[Sanya IV Litvyak]

Well, Gb Ethernet ports are useful to allow LAN-LAN connections of 1Gbps. Don't forget that this router, like most home routers, is also a four port switch.

It's true that Gb Ethernet ports are useful LAN to LAN but the WAN port is also advertised as a Gb Ethernet Port, although thinking about it having anything less would be worse considering the choices are 10/100/1000 ... so 100 Gb Ethernet port wouldn't make much sense if the router otherwise could handle ~250Mb/s bandwidth.. So it does make sense for Gb Ethernet ports for WAN but at the same time it's misleading since the consumer would expect the router to actually be able to achieve that bandwidth as well without the CPU being a bottleneck, had I known about that issue to begin with I'd never have gotten this router.

Also, sorry for the late reply, I just accepted that this router will never achieve the bandwidth I expected it to so I just gave up.

 

[wouterv]

Some thoughts:
After you verified the throughput directly from a PC to the modem (wired of course), the next step would be:
A router with the latest firmware (either stock or Asuswrt Merlin), hard reset the router and ONLY a minimal manual configuration to allow Internet access through the modem (do not enable other fucntions).
Wire the PC to a LAN port of the router and test the throughput again.
Make sure the cables and connectors are in good condition and properly seated.
Make sure the router and modem are on some distance of each other and they are on distance from other electronics to avoid disturbance.
After you checked the througput according the above, the next steps can be to use other functions of the router or do the same checks with a wireless connection.

 

[Klueless]

... upgraded my network from 100/10 to 500/50 and with that upgrade I got a new cable modem. Just by plugging my computer into the new modem and running a speed test I get the advertised speed of 500/50 (roughly, measured in Mb/s) but when I try through the Asus router (Modem in bridge mode) I get around 230-260 Mb/s down and 50 Mb/s up and looking at that download it's almost half of what I should be getting

Perhaps the difference is NAT overhead? Does download performance get a little better when you turn off wireless such that your only NAT table entry would be your single hardwired PC? (Might have to reboot to flush the table?)

I don't know, I'm just kinda curious.

 

[Sanya IV Litvyak]

Some thoughts:
After you verified the throughput directly from a PC to the modem (wired of course), the next step would be:
A router with the latest firmware (either stock or Asuswrt Merlin), hard reset the router and ONLY a minimal manual configuration to allow Internet access through the modem (do not enable other fucntions).
Wire the PC to a LAN port of the router and test the throughput again.
Make sure the cables and connectors are in good condition and properly seated.
Make sure the router and modem are on some distance of each other and they are on distance from other electronics to avoid disturbance.
After you checked the througput according the above, the next steps can be to use other functions of the router or do the same checks with a wireless connection.

I don't want to do that because I can't remember how to set up DNSCrypt, I had an issue with the time on the router which caused the certificates to be denied and I had to solve that by editing some script, don't trust myself to be able to do that again and don't really care enough about the issue anymore to go through that again. (not used to linux and doing the dnscrypt setup before took me many many hours to fix in an unfamiliar environment)

Perhaps the difference is NAT overhead? Does download performance get a little better when you turn off wireless such that your only NAT table entry would be your single hardwired PC? (Might have to reboot to flush the table?)

I don't know, I'm just kinda curious.

I disabled 2.4GHz and 5GHz radio and rebooted the router and then did a speed test, ~260-270Mb/s down depending on test, so maybe a minor increase which might be logical considering less devices and radio off = less CPU usage from them leaving more resources when the test is being performed but at the same time they don't leave enough for the test to reach 50oMb/s
Edit: Actually nevermind, I enabled the wireless radios again and redid the tests and still got the same result, so it just seems to be generally between 240-270Mb/s. Also I tried disabling several things like firewall, SSH etc and none made any difference.

Edit: This really is a non-issue now considering my rt-n66u seems to have broken down after updating the firmware to 380.57
I noticed that some options were "corrupted" (set to something but not actually set to that and couldn't change the settings) so I used the web UI to perform a reset to factory defaults.. After that no settings stick at all, I complete the setup wizard but after that it asks me to log in and refuses the login details I made during the setup and it'll only allow admin/admin.. after logging in with that then it won't let me change any settings, once I try it just re-prompts for username/password and if I enter then it just takes me to the main web UI page without changing any settings... I can't upload a new firmware, I can't factory reset and the reset on the back does seemingly nothing.. To be frank I've now gotten sick and tired of this router, I've gone back to using the router on the modem which actually works amazingly (5GHz wireless on Asus gave me ~10Mb/s in my room, 5GHz wireless on Compal router gives me ~100Mb/s in my room) .. The only downside with this router for me is the lack of network wide DNSCrypt.

Edit: Fixed the router by resetting nvram and restoring firmware via rescue, after that it seems to be working fine, getting the right speeds now as well (500Mb/s down) so now I'm just going to install DNSCrypt again and see if I can get that working. So all of you saying to reset the router, you were right! We'll see how it works after DNSCrypt is installed though, I have a feeling that's what made it slow down before, but we'll see.

 

[Klueless]

I disabled 2.4GHz and 5GHz radio and rebooted the router and then did a speed test, ~260-270Mb/s down depending on test, so maybe a minor increase ...

Let's do a quick recap. Reduced CPU demands slightly and got a slight increase in performance.

Lost everything (sorry to hear that), came back stock and huge increase in performance.

Some software features are mutually exclusive with hardware acceleration.

Due to high costs around here we've only a 15 x 1.5 Mbps service. And, until recently, we've had 20 plus grumpy users competing for bandwidth. Couldn't afford to throw bandwidth at the problem so we threw software engineering at it (traffic monitoring, QoS, etc.) instead. Lost hardware acceleration but CPU keeps up fine with 15 Mbps and the software makes sure each user gets a fair turn so, believe it or not, everyone is happy.

But, at some point, pick a number, 100, 200 Mbps, the CPU can't keep up so you need hardware acceleration. In my case I'd gladly give up traffic monitoring for a 250 Mbps link.

In your case I would think DNSCrypt has to tinker with each and every packet thus you are bypassing hardware acceleration and the CPU can't keep up with those speeds?

I'm thinking you will have to make a choice between speed or features, can't have your cake and eat it too.

But you will know soon, like when you reload DNSCrypt. Here's hoping that I am wrong!

Do keep us posted.

 

[Sanya IV Litvyak]

Let's do a quick recap. Reduced CPU demands slightly and got a slight increase in performance.

Lost everything (sorry to hear that), came back stock and huge increase in performance.

Some software features are mutually exclusive with hardware acceleration.

Due to high costs around here we've only a 15 x 1.5 Mbps service. And, until recently, we've had 20 plus grumpy users competing for bandwidth. Couldn't afford to throw bandwidth at the problem so we threw software engineering at it (traffic monitoring, QoS, etc.) instead. Lost hardware acceleration but CPU keeps up fine with 15 Mbps and the software makes sure each user gets a fair turn so, believe it or not, everyone is happy.

But, at some point, pick a number, 100, 200 Mbps, the CPU can't keep up so you need hardware acceleration. In my case I'd gladly give up traffic monitoring for a 250 Mbps link.

In your case I would think DNSCrypt has to tinker with each and every packet thus you are bypassing hardware acceleration and the CPU can't keep up with those speeds.

I'm thinking you will have to make a choice between speed or features, can't have your cake and eat it too.

But you will know soon, like when you reload DNSCrypt. Here's hoping that I am wrong!

Do keep us posted.

I now have DNSCrypt up and running again with two resolves (dnscrypt.eu-dk and -nl) and still getting ~500Mb/s down so it's finally running as it should. Also the dnscrypt setup was easier now than it was before in my opinion, except the multiple resolver setup where I had to go to an archival site to get the instructions since they were removed from the thread.. but yeah, everything is working fine now, assuming something was wrong with my previous setup (and perhaps corrupted NVRAM?)

 

[Klueless]

I now have DNSCrypt up and running again with two resolves (dnscrypt.eu-dk and -nl) and still getting ~500Mb/s down

I am very happy I was wrong! (Guess I'll be having crow instead of cake : -)