RT-AC56U Slower WAN over WLAN and strange WLAN speed "hiccups"

[maad11]

Hi Everyone,

I have a quite stable VDSL 40/4 Mbps connection that have been handled so far by a Sagem Fast 3764 provided by my ISP. Since the Sagem unit has its limitations, I have been looking around for a new router and the RT-AC56U got my serious attention and high hopes as well.
I had it delivered yesterday, immediately upgraded to the most recent official firmware available (3.0.0.4.374_339), set it up - i.e. put Sagem in bridge mode, connected the AC56 over PPPoE and to be honest - got very quickly disappointed by its performance.
First of all - there is a serious drop in my WAN speed over Wifi - both 2.4 and 5 GHz networks.
Below, there is a speed test of my internet connection via LAN:
http://www.speedtest.net/my-result/3158666074
and this was also more or less what I was getting from Sagem Wifi, but from Asus I get usually 10 or 20 Mbis less, this is the same server measured a minute after the above test via AC56U Wifi:
http://www.speedtest.net/my-result/3158672577
Only half speed... any ideas?
I have 2 networks: 2.4GHz and 5.2GHz, both "WPA2-Personal" protected with MAC filter enabled. All the rest of the settings - more or less as default. QoS disabled.
The "speed drop" takes place during connections via both of them. However, I must say that from time to time (very rarely) I manage to get full WAN speed over the WLAN - go figure...

The second issue is some kind of "hiccups" that I am having on the 2.4 GHz network - from time to time, with a good or decent signal the connection speed goes down to 1 or 2 Mbps... and than after few minutes goes back up itself or you need to reconnect.
Please kindly take a look at the screen below, I was sitting about 1.5 - 2 meters away from the router, the signal was -32 dB, yet the the speed dropped to "impressive" 2 Mbps...:
https://www.dropbox.com/s/qlhy2o6yh6cdr7y/wireless_1.PNG

Any ideas what's going on?

I will really appreciate your help and assistance. Maybe some tweaks would help or I am doing something wrong?
Thanks in Advance
BR

 

[ikoul]

Do you specify your channels or let the router choose?

I've found that the auto setting seems to have strong preferences for some channels (for me 6 on 2.4Ghz and 149 on 5Ghz), despite them not necessarily being the best ones for throughput. Try choosing different ones and see if it helps (you don't seem to have many neighboring wireless networks, but there could be other sources of interference or those two co-channel ones could be surprisingly busy).

Also, the settings in the router's advanced settings tab (and the ones in the drivers for your network adapter) can make a huge difference, so playing with those can be a worthwhile (and maybe frustrating and time consuming for some people) task.

With the right settings an AC56U should be able to handle way more than 40Mb/s over wifi on both bands.

 

[maad11]

Thanks for the reply.
The channel control was set for Auto. I tried to choose a few new ones manually, but unfortunately it does not seem to help - still no higher than 30 Mbps. Meanwhile I had another 2 "hiccups" or "speed freezes" - only 1 Mbps while sitting 2m away from the router, grrrrgh.
Besides trying to change Tx transmit power (that did not seem to have any effect either) I have not tried to play with the "professional" wifi settings - frankly, I do not really know what to do there
As you wrote - it seems that the router such as the AC56U should handle 40 Mbits easly, I really do not get it. Maybe I got a faulty one... I have yo admit that it is getting seriously depressing... and BTW I am probably in top 3 users generating majority of traffic on the speedtest.net over last couple days
BR

Edit:
as I wrote earlier, sometimes it can perform:

but a minute later, back to "normal"

 

[sinshiva]

you probably desperately need to tweak your MTU for starters or it'll never run as efficiently as cable. since you enjoy speedtesting leave router wan mtu at 1500 or 1492 depending on that the isp told you.

set a wired pc's mtu to 1488 and speed test. drop to 1486 and do it again. keep going until a test causes your download bandwidth to be the highest you've seen. it will slowly drop til you reach it. i needed 1456 without pppoe, with pppoe i believe it should be higher (contrary to the 1492 vs 1500 thing, i know, but pppoe i guess is actually relatively efficient.

afterwards, you' set the wan mtu to what you found worked best. if you get that, i have more to add, such as getting the router's lan ports mtu to match. not possible without using asuswrt-merlin or ddwrt atm.

 

[ikoul]

you probably desperately need to tweak your MTU for starters or it'll never run as efficiently as cable. since you enjoy speedtesting leave router wan mtu at 1500 or 1492 depending on that the isp told you.

set a wired pc's mtu to 1488 and speed test. drop to 1486 and do it again. keep going until a test causes your download bandwidth to be the highest you've seen. it will slowly drop til you reach it. i needed 1456 without pppoe, with pppoe i believe it should be higher (contrary to the 1492 vs 1500 thing, i know, but pppoe i guess is actually relatively efficient.

afterwards, you' set the wan mtu to what you found worked best. if you get that, i have more to add, such as getting the router's lan ports mtu to match. not possible without using asuswrt-merlin or ddwrt atm.

Seems unnecessary if he's already getting the full speed of his connection over LAN and just wants wifi to work at the same level.

maad11, I'll try to post some screenshots of my professional settings later and you can see if they help. Might be pretty late in Poland by then though.

 

[maad11]

Thanks for the tip with the MTU tweaking. I will give it a try when I find some more time.
It really makes me wonder howcome it has its peaks and can do around 40 Mbps but most of the time just cuts fown the bandwith stubbornly.

What is also seriously annoying is those "speed freezes" at 2.4 network. It happened a couple times already tonight. The wifi at my laptop stalls at around 1 Mbps when my phone at the same time and being next to the laptop connects normally

Edit:

I'll try to post some screenshots of my professional settings later and you can see if they help. Might be pretty late in Poland by then though.

Thanks a lot ikoul,

 

[sinshiva]

i'm not sure how wifi does padding or if it relies on the router via ethernet, which is why i think he should eliminate that, at least

[edit/] here's an example. my most efficient MTU is 1456; least efficient MTU possible while being as high as possible for me is 1457, one more than the best.

with 1456 MTU, i speedtest at 10.15 down, 0.75 up on my 10/768 rated dsl
with 1457, i get 9.80 down and 0.6 up.

In addition, things are more prone to stall, which i suspect is more pronounced over wifi.

He says he's supposed to be getting 4up, but his speedtests show 3.85 which seems quite low and indicative of a rather inefficient MTU.

The MTU thing is far more important for DSL than cable, which is to say not at all. they get to set 1500 and forget it.

eitherway, good luck

 

[ikoul]

My setting screenshots: http://imgur.com/a/67vTE/all

Some of the options might not be there for you because of router differences.
Also, a lot of people report getting better results with beamforming off for 2.4ghz. I can't remember if the AC56 has beamforming settings or not.

 

[maad11]

ikoul - thanks a lot.
It turns out that mine settings are not that much different... I was trying to play with those, but unfortunately I can not see any significant improvement.
I also updated the firmware of my laptop wifi network card (intel n6205) - and still nothing different
It is really frustrating, so considering the "not so good" range (at least worse than my expectations) I think I will try to return the router (not so easy in Poland) and start the hunting all over again.
Anyway - thanks a lot for your support, really appreciated.
BR

 

[Injuis]

ikoul - thanks a lot.
It turns out that mine settings are not that much different... I was trying to play with those, but unfortunately I can not see any significant improvement.
I also updated the firmware of my laptop wifi network card (intel n6205) - and still nothing different
It is really frustrating, so considering the "not so good" range (at least worse than my expectations) I think I will try to return the router (not so easy in Poland) and start the hunting all over again.
Anyway - thanks a lot for your support, really appreciated.
BR

Yeah... this is an issue with this router. I reported the exact same problem here: http://www.smallnetbuilder.com/forums/showthread.php?t=13774

No fix in sight either.

 

[maad11]

Hi Everybody,
Just a quick update - I managed to return the router, and since the AC68 was over my budget I got RT-N66U.
First impressions running Merlin FW- looks like WAN connection is faster and more stabile, 2.4 GHz range is way, way better - day and night comparing to AC56, but... I am still having issues with the 2.4 GHz speed drops on my laptop After connecting to the network, sitting 1m away from the router, within several minutes I get impressive speed of 1 - 2 Mbps. Seems like the intel n6205 hates Asus 2.4 GHz for some reason.
Anyway, thanks again everyone for trying to help.
BR

Edit:
Looks like forcing my Intel network card to use only 20 MHz at 2.4GHz did the trick and there is no more speed hiccups occurring.

 

[RMerlin]

Edit:
Looks like forcing my Intel network card to use only 20 MHz at 2.4GHz did the trick and there is no more speed hiccups occurring.

I don't know how often this has been posted on these forums, but once more for other users who still haven't seen it:

40 MHz on the 2.4 GHz band is a bad idea, and WILL lead to stability issues.