As described in my last blog-entry I had a very unstable internet connection. After complaining many times Vodafone had send a technician who adjusted the gain of the cable amplifier.
After that adjustment my internet connection has been much better, but we still faced intermittent issues. The Downlink and the Uplink quality varied very much. It took Vodafone again multiple escalations over multiple month until they fixed the issue completely. It turned out that the amplifier had to be exchanged.
It took Vodafone 10 month and many escalations to fix this issue!
I would like to share the how the situation has to look like for a working configuration.
The gain for the channels has to be in the following ranges:
- QAM 64: 50-66 dBuV
- QAM 256: 56-72 dBuV
- 96 – 110 dBuV
I found in some forums that the Signal to Noise values for the Download channels should be larger than 34dB. A snapshot of the modem values show that all requirements are met at the moment.
So this looks fine.
But there is another very important aspect which has to be ensured so that the internet connection works fine:
- the gain and signal to noise has to be stable over the time !
In this setup the cable modem shows
- a ratio of “Correctable Codewords”/”Unerrored Codewords” less than 0,0001
- a ratio of “Uncorrectable Codewords”/”Unerrored Codewords” less than 0,00001
|Signal Stats(Codewords)||Bonding Channel ID|
|Total Unerrored Codewords||2028181539||2026089866||2026088914||2026092832||445805463||445803690||445805601||445805767|
|Total Correctable Codewords||8766||9986||11675||9220||12279||14709||12038||13012|
|Total Uncorrectable Codewords||1156||1189||608||111||915||854||933||586|
A single iperf3 stream then shows the expected results (200Mbit/12MBit)
iperf3 -c speedtest.serverius.net -p 5002 -R -t 30 [ ID] Interval Transfer Bandwidth [ 4] 0.00-30.00 sec 681 MBytes 191 Mbits/sec receiver
iperf3 -c speedtest.serverius.net -p 5002 [ ID] Interval Transfer Bandwidth Retr Cwnd [ 4] 0.00-10.00 sec 14.3 MBytes 12.0 Mbits/sec receiver
For your reference I have attached the charts where the difference of the amplifier is shown.
As you would have guessed the amplifier was exchanged on Thursday 😉