Over the last few weeks been having several occurrences where am getting packet loss on my connection. This shows up on my BQM monitor and also when am trying to stream on twitch, resulting in around 5% dropped frames (normally its 0%). This generally resolves after a day or 2, which am guessing is when someone in VM notices a problem on their network and bounces the faulty device.
The issue is currently ongoing right now as shown on my BQM live graph and snapshot:
Thanks for posting. Okay so I have run checks and no issues showing, all levels are fine etc. There is a provisioning issue on the base of your account however, which could be causing it. It's a known issue we're aware of. I will come back to you when have an update.
I believe that the 25.8 MHz channel is particularly prone to interference and I’m also sure that I read recently that VM are planning/working on phasing out use of this channel where possible.? Hopefully someone more knowledgable about VM’s plans will be able to confirm or deny - although probably anyone who actually knows what VM’s plans are, is not at liberty to say!
Now having said that, yes ideally all four channels are supposed to be running at 64 QAM but DOCSIS is designed to ‘sort of’ self adjust itself to compensate for local conditions. So if a particular channel can’t get a reliable connection at a modulation of 64 QAM it will drop to 32, and if that works OK it’ll stay there and ramp back up if and when the conditions improve.
Without doing into all the maths and details of QAM, the difference between 64 and 32 isn’t actually that much, each ‘symbol’, which you can think of as a packet of data transmitted all at once, (OK it’s not really a data packet but work with me on this one), is composed of 6 bits for 64 QAM rather than 5 bits for 32 QAM. Incidentally why 6 bits or 5 bits?; 2^6 is 64, 2^5 is 32 etc.
Take a look at the upstream stats from the Hub, what you see for each channel is something like 5120 ksym/sec at 32 QAM (or ideally 64QAM), so, somewhat crudely, each channel has a capacity of 5120 x 1000 (it’s kilosymbols per second) x 5 (QAM32 is 5 bits per symbol) or 25,600,000 bits per second (or 25 Megabits per second). Compare this with QAM 64 which is (I’ll leave it to you to do the maths) is only a 17% (roughly) reduction in capacity. And that’s only on one of the four bonded channels.
So, if a single channel drops to 32 QAM, then yes, that is an indication of noise ingress on the connection, but it really isn’t the end of the world