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R8000 jitter extremely high on Skype voice calls

rutilate
Tutor

R8000 jitter extremely high on Skype voice calls

When running Skype voice call over a wireless connection between my Macbook Pro and Netgear Nighthawk R8000 (both in the same room), jitter is commonly in the 300-400 range and sometimes up into the 1800 range, and incoming call quality is abysmal with significant speech brownouts and delays.  When I connect via Cat5e cable, the jitter goes down to 20-100ms, but call quality occasionally suffers with fewer incoming speech brownouts and delays.  

 

  • Comcast service is 105 mbps down, 10 up. Speedtest typically shows 120/12 during the day at the times I'm making the call. I'm certainly oversubscribed for a single person voip capacity!
  • Pingtest typically gives me an A rating, with 0 packet loss, ping of 30ms, and jitter of ~15ms.  I can post details if necessary.
  • Running 2014 Macbook Pro (haven't upgraded to 10.10), Skype for Mac 7.7
  • Router and Macbook Pro are in the same room
  • Wifi TX rate is ~850 Mbps, wired is 1GB
  • Rebooting the router/modem doesn't seem to make a significant difference
  • Comcast claims everything is working fine on their end

 

When I first start a Skype voice call via the wireless connection, the jitter is 20ms upon first connection but quickly rises to an average of 400ms and even up to 1800ms and the call is dropped. Roundtrip is about 105ms, 4.1% packet loss. For this particular test, pingtest showed 76ms ping, 46ms jitter:  http://www.pingtest.net/result/132566282.png

 

When I turn off the laptop wifi, causing it to use the ethernet connection through my apple display, jitter rapidly falls to 20ms, roundtrip of 115ms. The pingtest shows 50ms ping, 18ms jitter: http://www.pingtest.net/result/132566282.png

 

I have configured the QOS to give my laptop the highest priority, but it doesn't allow any finer configuration than this.

 

How can I clean up this awful call performance?  I run a business out of the home and the poor phone quality is killing me.  

 

 

Message 1 of 4

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TheEther
Guru

Re: R8000 jitter extremely high on Skype voice calls

TL;DR Try disabling Dynamic QoS. Leave WMM on, however. Switch to the least congested Wi-Fi channel. Check Wi-Fi signal strength on your Mac. Use 5 GHz.

 

While Netgear generally recommends disabling QoS for Internet connection speeds of 300 Mbps or higher, I think that's too conservative. Netgear's QoS implementations have trouble managing high speed links; IOW, enabling QoS worsens performance. QoS should only be used on lower speed Internet connections where congestion is likely.  For the typical use case with 1 or 2 video streams, and a smattering of web surfing, email and gaming, that amounts to 10 to 20 Mbps in the downstream direction. Your 105 Mbps connection will likely never saturate in the downstream direction. And while your upstream bandwidth is only 10 Mbps, unless you happen to uploading photos or videos, there is little chance it will be fully used. Even Skype traffic requirements are modest (1.5 Mbps for HD video, much less for audio only). My recommendation is to turn off Dynamic QoS on your R8000.

 

You should survey your area for the presence of other Wi-Fi networks. Someone may be using the same Wi-Fi channel as your network. You will want to switch to the least congested channel. Use the desktop Genie app, or freeware programs like Vistumbler or Acrylic Wi-Fi.

 

Finally, it wouldn't hurt to double check the strength of the Wi-Fi signal as reported by your Macbook. Hold the option key down and click on the Wi-Fi symbol at the top of your screen. This will display information about the Wi-Fi signal, as shown below, for example:

Mac Wi-Fi signal stats

You will want to make sure that the RSSI and Tx Rates are good. In fact, you should see numbers comparable to mine since your Mac and R8000 are in the same room. By all means, use the 5 GHz network!

 

Hope this helps.

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Message 2 of 4

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TheEther
Guru

Re: R8000 jitter extremely high on Skype voice calls

TL;DR Try disabling Dynamic QoS. Leave WMM on, however. Switch to the least congested Wi-Fi channel. Check Wi-Fi signal strength on your Mac. Use 5 GHz.

 

While Netgear generally recommends disabling QoS for Internet connection speeds of 300 Mbps or higher, I think that's too conservative. Netgear's QoS implementations have trouble managing high speed links; IOW, enabling QoS worsens performance. QoS should only be used on lower speed Internet connections where congestion is likely.  For the typical use case with 1 or 2 video streams, and a smattering of web surfing, email and gaming, that amounts to 10 to 20 Mbps in the downstream direction. Your 105 Mbps connection will likely never saturate in the downstream direction. And while your upstream bandwidth is only 10 Mbps, unless you happen to uploading photos or videos, there is little chance it will be fully used. Even Skype traffic requirements are modest (1.5 Mbps for HD video, much less for audio only). My recommendation is to turn off Dynamic QoS on your R8000.

 

You should survey your area for the presence of other Wi-Fi networks. Someone may be using the same Wi-Fi channel as your network. You will want to switch to the least congested channel. Use the desktop Genie app, or freeware programs like Vistumbler or Acrylic Wi-Fi.

 

Finally, it wouldn't hurt to double check the strength of the Wi-Fi signal as reported by your Macbook. Hold the option key down and click on the Wi-Fi symbol at the top of your screen. This will display information about the Wi-Fi signal, as shown below, for example:

Mac Wi-Fi signal stats

You will want to make sure that the RSSI and Tx Rates are good. In fact, you should see numbers comparable to mine since your Mac and R8000 are in the same room. By all means, use the 5 GHz network!

 

Hope this helps.

Message 2 of 4
rutilate
Tutor

Re: R8000 jitter extremely high on Skype voice calls

TheEther, thanks for the response.

 

I'm on 5Ghz network, TX Rate down from the router to the mac is 700-850Mpbs.

 

I moved one of my networks from 149 to 161 to overcome overlap, turned off QOS. I'll test the calls tomorrow and report back in.

 

Message 3 of 4
rutilate
Tutor

Re: R8000 jitter extremely high on Skype voice calls

I've run the system for two days and found that the calls are quite spectacular now!  I think that turning off the QOS was the trick. Who would think that disabling such a highly touted feature would be a good thing?

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