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Xfinity throttling - not achieving paid throughput levels
I've read other posts on xfinity performance and haven't seen any clear answers from Xfinity. I've been running performance testing and observing that xifinity network is inconsistent. I'm running tests over a laptop hard wired directly to the 2.5G port on the xfinity router with a CAT6A cable. I confirmed the network adapter is set to 1000/1000 and is capable of achieving speeds equal to my xfinity subscription of 1200 DL / 40 UL via CLI speedtest.
C:\speedtest>speedtest.exe
Speedtest by Ookla
Server: Comcast - Seattle, WA (id: 1782)
ISP: Comcast Cable
Idle Latency: 13.46 ms (jitter: 1.37ms, low: 12.51ms, high: 15.27ms)
Download: 939.34 Mbps (data used: 1.1 GB)
23.59 ms (jitter: 4.09ms, low: 9.81ms, high: 76.16ms)
Upload: 41.29 Mbps (data used: 28.3 MB)
5.55 ms (jitter: 2.15ms, low: 4.02ms, high: 59.63ms)
Packet Loss: Not available.
Next, I ran iperf3 tests to run interative tests over time. The throughput on xfinity is very inconsistent and appears to be throttling. The throughput starts out high (800+ mbps) but drops down to sub 100mbps with an overall average of 340mbps. This is way shy of the 1000mbs (network interface limit) I would expect paying for 1200mbps DL. I masked the server IP for privacy/security.
C:\iperf3.17_64>iperf3 -c xxx.xxx.xxx.xxx -p 5000 -t 30 -R
Connecting to host xxx.xxx.xxx.xxx, port 5000
Reverse mode, remote host xxx.xxx.xxx.xxx is sending
[ 5] local xxx.xxx.xxx.xxx port 57810 connected to xxx.xxx.xxx.xxx port 5000
[ ID] Interval Transfer Bitrate
[ 5] 0.00-1.02 sec 76.1 MBytes 629 Mbits/sec
[ 5] 1.02-2.00 sec 79.4 MBytes 673 Mbits/sec
[ 5] 2.00-3.01 sec 106 MBytes 885 Mbits/sec
[ 5] 3.01-4.01 sec 105 MBytes 876 Mbits/sec
[ 5] 4.01-5.02 sec 107 MBytes 896 Mbits/sec
[ 5] 5.02-6.00 sec 77.9 MBytes 661 Mbits/sec
[ 5] 6.00-7.01 sec 64.2 MBytes 537 Mbits/sec
[ 5] 7.01-8.01 sec 67.6 MBytes 565 Mbits/sec
[ 5] 8.01-9.00 sec 68.0 MBytes 577 Mbits/sec
[ 5] 9.00-10.01 sec 70.6 MBytes 590 Mbits/sec
[ 5] 10.01-11.01 sec 75.4 MBytes 630 Mbits/sec
[ 5] 11.01-12.02 sec 63.4 MBytes 528 Mbits/sec
[ 5] 12.02-13.00 sec 14.5 MBytes 123 Mbits/sec
[ 5] 13.00-14.00 sec 10.2 MBytes 85.6 Mbits/sec
[ 5] 14.00-15.01 sec 11.2 MBytes 93.9 Mbits/sec
[ 5] 15.01-16.01 sec 10.5 MBytes 87.8 Mbits/sec
[ 5] 16.01-17.00 sec 10.0 MBytes 84.8 Mbits/sec
[ 5] 17.00-18.01 sec 11.5 MBytes 95.9 Mbits/sec
[ 5] 18.01-19.01 sec 13.0 MBytes 109 Mbits/sec
[ 5] 19.01-20.00 sec 13.0 MBytes 110 Mbits/sec
[ 5] 20.00-21.01 sec 14.9 MBytes 124 Mbits/sec
[ 5] 21.01-22.01 sec 15.4 MBytes 128 Mbits/sec
[ 5] 22.01-23.02 sec 16.2 MBytes 136 Mbits/sec
[ 5] 23.02-24.00 sec 17.9 MBytes 152 Mbits/sec
[ 5] 24.00-25.01 sec 18.6 MBytes 156 Mbits/sec
[ 5] 25.01-26.01 sec 19.6 MBytes 165 Mbits/sec
[ 5] 26.01-27.01 sec 15.4 MBytes 129 Mbits/sec
[ 5] 27.01-28.01 sec 14.5 MBytes 122 Mbits/sec
[ 5] 28.01-29.01 sec 13.9 MBytes 116 Mbits/sec
[ 5] 29.01-30.00 sec 13.6 MBytes 115 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-30.03 sec 1.19 GBytes 340 Mbits/sec 3226 sender
[ 5] 0.00-30.00 sec 1.19 GBytes 340 Mbits/sec receiver
iperf Done.
I can repeat this test, at different times of the day and the results are always the same. There is a massive swing from high to low throughput, usually 75%-90% decrease in throughput.
Using the same laptop, on a different (non-xfinity) network, running the same iperf performance test to the same iperf server, I get the following results:
C:\iperf3.17_64>iperf3 -c xxx.xxx.xxx.xxx -p 5000 -t 30 -R
Connecting to host xxx.xxx.xxx.xxx, port 5000
Reverse mode, remote host xxx.xxx.xxx.xxx is sending
[ 5] local xxx.xxx.xxx.xxx port 64861 connected to xxx.xxx.xxx.xxx port 5000
[ ID] Interval Transfer Bitrate
[ 5] 0.00-1.00 sec 123 MBytes 1.03 Gbits/sec
[ 5] 1.00-2.00 sec 140 MBytes 1.17 Gbits/sec
[ 5] 2.00-3.01 sec 143 MBytes 1.19 Gbits/sec
[ 5] 3.01-4.01 sec 141 MBytes 1.18 Gbits/sec
[ 5] 4.01-5.00 sec 140 MBytes 1.19 Gbits/sec
[ 5] 5.00-6.01 sec 144 MBytes 1.20 Gbits/sec
[ 5] 6.01-7.01 sec 143 MBytes 1.19 Gbits/sec
[ 5] 7.01-8.00 sec 112 MBytes 955 Mbits/sec
[ 5] 8.00-9.01 sec 130 MBytes 1.08 Gbits/sec
[ 5] 9.01-10.01 sec 132 MBytes 1.11 Gbits/sec
[ 5] 10.01-11.01 sec 138 MBytes 1.16 Gbits/sec
[ 5] 11.01-12.00 sec 129 MBytes 1.10 Gbits/sec
[ 5] 12.00-13.00 sec 137 MBytes 1.14 Gbits/sec
[ 5] 13.00-14.00 sec 137 MBytes 1.15 Gbits/sec
[ 5] 14.00-15.00 sec 133 MBytes 1.12 Gbits/sec
[ 5] 15.00-16.00 sec 139 MBytes 1.17 Gbits/sec
[ 5] 16.00-17.00 sec 129 MBytes 1.08 Gbits/sec
[ 5] 17.00-18.00 sec 142 MBytes 1.19 Gbits/sec
[ 5] 18.00-19.00 sec 140 MBytes 1.18 Gbits/sec
[ 5] 19.00-20.00 sec 139 MBytes 1.16 Gbits/sec
[ 5] 20.00-21.00 sec 142 MBytes 1.19 Gbits/sec
[ 5] 21.00-22.00 sec 142 MBytes 1.19 Gbits/sec
[ 5] 22.00-23.00 sec 115 MBytes 967 Mbits/sec
[ 5] 23.00-24.00 sec 122 MBytes 1.03 Gbits/sec
[ 5] 24.00-25.00 sec 113 MBytes 946 Mbits/sec
[ 5] 25.00-26.00 sec 124 MBytes 1.04 Gbits/sec
[ 5] 26.00-27.00 sec 126 MBytes 1.06 Gbits/sec
[ 5] 27.00-28.00 sec 124 MBytes 1.04 Gbits/sec
[ 5] 28.00-29.00 sec 123 MBytes 1.03 Gbits/sec
[ 5] 29.00-30.00 sec 120 MBytes 1.01 Gbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-30.01 sec 3.87 GBytes 1.11 Gbits/sec 3152 sender
[ 5] 0.00-30.00 sec 3.87 GBytes 1.11 Gbits/sec receiver
iperf Done.
The change from high 1.2gbps to low 946mbps is minimal (20%) as compared on the xfinity network.
Xfinity - Why am I not able to get consistent performance and throughput anywhere close to the level of throughput (1200mbps DL) that I am paying for? I would expect executing performance testing tools, I would achieve throughput anywhere in the 800-1200 mbps consistently, not a range up to 90% off my subscription levels. This explains when I'm working from home, all file transfers from work to home take exponentially longer than on other networks.
Thanks
XfinityDemitrius
Official Employee
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1.3K Messages
3 months ago
Hey @whipple, Thank you for visiting our official Xfinity Forums Community support page. We greatly appreciate you taking the time to share your experience regarding the Xfinity Internet connection. I would be more than happy to offer my assistance looking into this further for you. Have you attempted to verify that the coax cable is in good condition such as no hard bends, kinks, bite marks, or cuts that could interfere with the services?
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EG
Expert
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106.9K Messages
2 months ago
@whipple @XfinityBenjaminM
Please circle back here and post any possible solutions for the issue here in these open public forums so that all readers here may benefit from the exchange / info. This is in keeping with the spirit for which these public help forums were originally intended. Thank you.
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