Link to home
Create AccountLog in
Avatar of ccampbell15

asked on

Problems with QOS and DD-wrt

I’m having some difficulty setting up QOS using DD-WRT.  I have Time Warner coming in going to a Buffalo WZR-HP-G300NH with DD-wrt V24-SP2 (8/7/10) std.   That router feeds a Vonage router (vdv21-vd).  

 Incoming bandwidth ( with QOS disabled on the Buffalo is 30.1 down and 4.91 up. I’m trying to setup QOS service because when my backup is going on my voice quality clips.  I can hear the other party fine but they tell me I’m clipping and it’s just a real bad connection. The backup happens on a different system than my main workstation which I am using for this test.

I set QOS (not too interested in scripts or Tomato) as follows:

QOA settings
      Port: Wan
      Packet scheduler: HTB
      Uplink: 4400
      Downlink: 27000
      Optimize for gaming: unchecked

Services priority
      Httpaudio: premium
      Httpvideo: express

Netmask Priority  - blank

Mac priority
The mac address of the Vonage router: 100 up,  100 down
The mac address of my main PC nic:  4300 up, 25000 down

Default bandwidth level
      4300 up, 2500 down

When I enable QOS and run a speedtest I then get:
      Ping: 48mS
      Down: 19.4M
      Up: 3.74M

There is nothing besides the speedtest going on at this time.

With the QOS enabled I get a MOS score of 4.2 with 0.9mS jitter. With it off I get a MOS score of 4.1 with 1mS jitter.

I don’t understand why the bandwidth takes a hit at all with no activity on the phone.


I attached a pdf of the QOS page from the router
Avatar of Aaron Tomosky
Aaron Tomosky
Flag of United States of America image

the problem with qos and cable modems is it's not a flat constant speed like a fiber connection. a cable modem connects slower at first then gives you some extra speed as it ramps up. qos doesn't like this. I personally have a cable modem at home from the same company and to get qos to work well I had to trim it down to my listed speed, not the speed I could get when the faster part kicks in. In your case it's probably 20mbit. Thats 2.4MB/sec which you can't get from most websites anyway but if you are doing p2p it will drop your overall vs. no qos. Even with a sonicwall or something enterprise grade, cable modems just don' t play nice with qos and you always get a slower speed that without.
Avatar of ccampbell15


If it was just dropping the download to 20M I'd be OK with that but it seems to trash the upload and give me 15% less on the download than what I programmed.  With the QOS setting set to 20M now and the others left the same I get 17.18M down, 2.6M up.

 I have a server on the LAN that is currently sending a lot of data upstream and it drops the uplink in 1/2.  Since I have the phone and my main workstation prioritized and the server not even mentioned I expected the test result to come back with the full 5M?  It also disrupts the quality of the outgoing audio on my phone.  

Perhaps I misunderstand what QOS can do for me?  I expected to have Audio remain clear in spite of what data might be going upstream.
Avatar of Aaron Tomosky
Aaron Tomosky
Flag of United States of America image

Link to home
Create an account to see this answer
Signing up is free. No credit card required.
Create Account
also, I think this is the fw I use on my similar buffalo routers, the wiki and routerdb show the much older version you have
Not sure I'm at the bottom of this but ended up with the following:

uplink and downlink set to 0
httpvideo and audion set to premium

I updated to the latest firmware (thanks)

Any further suggestions before I close this?

How does it work? Clear calls? Speedtest?
The audio seems to be Ok but video will freeze on occasion
Didin't have a change to check yet
I'll close this for now and update when I can.

Omce again, thanks!