Asus Rt-AC66U Capping Internet Speed to Around 35Mb/s

[hoomanra]

Hi.
My Router is Asus RT-AC66U.
Myissue in a nutshell: I have switched my internet from ADSL to Cable and now I can get internet speed around 70 Mbit/s. If I use the supplied cable modem directly (Netgear CG3000-2STAUS), my internet speed is around Download: 70 Mbit/s , Upload: 2 Mbit/s . However, when I set the cable modem to bridge mode and then connect it to the asus router, my internet speed gets halved (Download: 30 Mbit/s, Upload: 0.9 Mbit/s).
I am a professional. I tried everything. I couldn't fix the issue. I googled the issue and I realized there are other people with same problem as well:

http://www.overclock.net/t/1415568/...t-deliver-the-raw-modem-speed-to-lan-or-wi-fi

http://www.dslreports.com/forum/r28451445-Help-Just-got-RT-N66U-and-the-WAN-speed-is-capped-at-35Mb-

I tried another router (Dlink DIR-655). At first it was like asus (i.e. it capped my internet speed at around 30 Mbit/s) however, I could change a setting in its QoS section (selecting cable modem) and it fixed the issue! I could get speed around 70 Mbit/s with Dlink!
There is no such setting in Asus and I checked all the possibilities in the QoS section of the Asus Router and nothing fixed the issue.

Is there anyone that can help?

I personally believe it is a firmware bug. I have raised it to Asus. So far, I have not received any answer from them.

I read somewhere, if i flash the router firmware to dd-wrt, it would solve the problem. But if I do that, I will lose asus AICloud and I do not want to lose that.

 

[TonyH]

Hi,
Did you try with QoS disabled?

 

[RMerlin]

Cablemodems don't like when you change the MAC of the DHCP client (i.e. the router doing the DHCP changes). Turn off your modem for about 10 mins, then turn it back on, and try again. This should fully reset the connection with your ISP.

 

[hoomanra]

Thanks Guys.

As mentioned, I tried all the possibilities in Qos including disabling it. It did not fix the issue. It has nothing to do with the cable modem. As mentioned, I tried it with Dlink, and after chaning a setting, Dlink was performing fine.

However, after spending hours and hours, I sorted out the issue with below changes:
1) Setting the firewall to disabled (for both Ipv4 and Ipv6)
2) Turned off the cloud disk option

and bang! the issue is gone! I can even now connect with faster speed comparing to connecting to modem direct (80 Mb/s comparing to 70 Mb/s)!!

 

[RMerlin]

Thanks Guys.

As mentioned, I tried all the possibilities in Qos including disabling it. It did not fix the issue. It has nothing to do with the cable modem. As mentioned, I tried it with Dlink, and after chaning a setting, Dlink was performing fine.

However, after spending hours and hours, I sorted out the issue with below changes:
1) Setting the firewall to disabled (for both Ipv4 and Ipv6)
2) Turned off the cloud disk option

and bang! the issue is gone! I can even now connect with faster speed comparing to connecting to modem direct (80 Mb/s comparing to 70 Mb/s)!!

Disabling the firewall disables a large portion of the router's functionality such as port forwarding, traffic monitoring, QoS, etc... This isn't a good idea, and is not a solution.

 

[hoomanra]

Hi RMerlin,
After disabling the firewall, Traffic monitor and port forwarding still work.
I dont want Qos. I disabled that ages ago.

The following features wont work though:
- Responding Ping Request from WAN
- Filter Rules (URL Filter, Keyword Filter, Network services Filter)

As far as I can see, everything else works.

 

[djlk]

Same issue with RT-AC66U

I'm having the same issue with my RT-AC66U. I have Time Warner's 300mbps/10mbps service, and when using LAN (i.e. Cat 5e) into the modem I get 310/10 using Speedtest.net and other services. But when using LAN on the RT-AC66U (to a brand new Thinkpad T440S with 802.11 A/C) I am capped at about 37/10 (wired or wireless).

I've updated the firmware to 3.0.0.4.376_2524, turned off QOS, turned off the firewall and none of this made a difference (I've since turned the firewall back on). Other than throwing the router into access point mode and handing over router duties to the Arris DG1670A does anyone have any suggestions?

I think it might be a double NAT issue, but I'm not experienced enough to say for sure.

 

[jegesq]

Some advice with Arris DG1670 and RT-AC66U (long)

DJLK:

I spent a lot of time installing my new Arris DG1670A cable modem/router combo from TWC to get the new 300/20 speeds. Much time was wasted. I too have an RT-AC66U (actually two, one as a router, the second as a 5ghz only "repeater" located downstairs near my HTPC).

I agree your issue is probably double NAT. Here's how I solved the issue:

First things first, you need to configure the Arris DG1670 correctly, so that it works only as a cable modem and not a combo modem/router.

Connect a laptop or other computer directly to the Arris so you can get to the web-based GUI without difficulty. Note that If you've already "bridged" the Arris (by turning off NAT, as instructed below), the Arris will have a different internal IP address. The stock way to get in is through 192.168.0.1; if it's "bridged" the IP address changes to 192.168.100.1. Remember this because once you make the change to "bridged" you won't be able to get into the Arris using 192.168.0.1, and will need the new IP addy.

Also, you should know not to change the Arris password (and yeah, the user name is "admin" and the password is "password"). The reason is that TWC will freak out (so I'm told) since they'll be locked out of their leased modem, which they consider a no-no. Not sure why you'd want them in your modem anyway, but if you're leasing it, those are the rules. I'm going to buy a Motorola/Arris SB 6183 when they are available, but the DG1670 is what's here now.

Once you are into the Arris DG1670 web GUI, you need to make the following settings changes:

1) Basic System Setup:
A. "Basic Setup"-- uncheck "Routing Enabled"-- turn off routing so the RT-AC66U handles it;
B. "Wireless 2.4 ghz" --disable by unchecking "Enable Radio";
C. "Wireless 5.0 ghz"-- disable this too.
D. "2.4/5ghz WPS" --disable by unchecking the box

Click "Apply" to store changes.

2)WAN Setup

(Note, be sure to look at the links on the left of this page to do items B-D below):

A. Dynamic Configuration Settings-- Keep "DHCP Enabled" checked. This is so the modem gets the external IP from TWC. You only "uncheck" this if TWC has given you a fixed IP address (unlikely).

B. "Static" settings - ignore this page

C. Click the link for "Dynamic IPv6" settings page-- make sure that "enable" is checked. Click "Apply"

D. "Static IPV6" settings page --ignore this page.

3. LAN Setup

All changes you will make here are on the "LAN Settings" page. Ignore all the other links on left side of page)

Under LAN Settings:
A. "LAN IP Settings"-- Info here is irrelevant; it will become "greyed out" once you change Natting (below);
B. "DHCP Server Settings" -- make sure "Enable" is unchecked. Ignore the other DHCP settings info.

C. "DNS Override"-- This is unchecked (disabled)

D. "DNS Relay"-- This is unchecked (disabled)

***E. "NAT"-- Set "Nat Mode" to "Bridged" in the pulldown. THIS IS CRITICAL. YOU MUST BE IN "BRIDGE" MODE TO AVOID DOUBLE NAT.

F. "UPnP"-- I've left mine enabled (checked). I have no idea whether this does anything, because UpnP is enabled in the RT-AC66U also.

Click "Apply". IMPORTANT: Again the modem's IP address will be different and you'll need to reload the settings pages. You'll need to type the new IP address: 192.168.100.1.

4. Ignore the "2.4 Ghz Wireless" and "5.0 Ghz Wireless" tabs. Radios are off now.

5. Firewall Settings

A. Firewall Enable/Disable-- turn it off.
B. DoS Protection-- turn it off.
C. Block Pings-- turn it off.
D. IPSec Pass Through-- mine is "enabled". No idea whether it should be or not.
E. PPTP Pass Through-- mine is "enabled". Ditto.
F. L2TP Pass Through-- mine is "enabled". Ditto. ]
G. Block Fragmented IP Packets-- turn it off.

Click "Apply".

You can ignore all the other settings on the Arris.

Next:

1. Turn off (unplug) the Arris DG1670A.
2. Before plugging the Arris back in, plug in the WAN cable from your RT-AC66U into Port 1 of the Arris (the top port right below the USB).
3. Make sure RT-AC66U is plugged in and on.
4. Now plug the Arris back in and wait for it to lock onto a solid signal from TWC.

If you've messed anything up or it doesn't work, you can reset the Arris to factory defaults by holding the "reset" button in for at least 30 seconds.

My RT-AC66U's have Merlin 374.40 (I find that the newer 376.x firmware degrades performance and distance). Settings for WAN are: Set to "Automatic Type" for connection, enable WAN, enable NAT, enable UPnP, make sure "connect to DNS Server automatically" is checked. You shouldn't need to clone the MAC address (TWC doesn't require that), so leave the rest as is. Let the ASUS handle your firewall settings.

That's it. You should be good to go. My speeds are regularly 320/20 on Gigabit (wired), and 250-290/20 on 5ghz wireless (depending on attenuation, etc.).

Hope this helps you.

 

[jegesq]

A couple more things on speed

A few last adds:

1. Beware of the variability of some speed testing sites. Most of them use the same Ookla engine, so even though they look different, with different graphics, they are basically the same. Nevertheless, I've found as you probably have too that many of these sites behave quite differently even though they run the same basic tests (no doubt due to many variables, not just distance from the server). I used to depend on Speedtest.net, but lately I am getting sometimes wildly different numbers from that site. I've found the most accurate and reliable results are from AT&T's speed test site. at www.att.com/speedtest

2. Also, before you do a speed test, you will probably want to clear your browser's cache, delete temporary internet pages, and in extreme cases of erratic performance (which you mostly will see on the wireless side), you may even try deleting any saved or stored settings for your wireless adapter (you can actually delete the entire thing in Device Manager then have it "look for changes" and reinstall the adapter drivers.

Hope this helps save you some of the time I wasted setting up my Arris DG1670A from TWC.

 

[jegesq]

It's NOT your Asus router....it's the Arris Cable Modem

To both the OP and to DLJK,

In case I wasn't clear enough, the issue with slow speeds on TimeWarner Cable isn't with your router....the issue is with the settings on the Arris DG1670 combo cable modem/router and how it's set up by TWC. You need to change those settings on the Arris so that it acts as only a cable modem, and not as a router.

You need to turn off the built-in WiFi in the Arris, turn off NAT, and turn off the Arris firewall. All routing, NAT and firewall are handled by your ASUS router, not by the Arris.

 

[sfx2000]

All good tips - one other thing to check...

The Ethernet cable between the modem and the router - I've seen it more than once...

 

[jegesq]

Yes, make sure the cabling (all of it) is rated either Cat5e or Cat6. Older cabling will slow things down right from the start.

Also, if you can, make sure any cable splitter (if one is used) is installed by a qualified tech from TWC who can check line levels to be sure there's little or no signal loss.

 

[RubberCow]

Late reply here, but I just followed the steps that jegesq suggested above in post 8. Thank you, jegesq.

I also had to turn off my "Enable Smart QoS" under "Traffic Monitor" on my AC66U. Combined, my similar issue was resolved.

 

[sfx2000]

Late reply here, but I just followed the steps that jegesq suggested above in post 8. Thank you, jegesq.

I also had to turn off my "Enable Smart QoS" under "Traffic Monitor" on my AC66U. Combined, my similar issue was resolved.

Nice...