Level 2: Rookie

NBN on HFC - 100/40 plan with significant packet loss in the evening.

I'm on a Telstra HFC NBN 100/40 plan, having switched from 100 Mbs Cable, and am experiencing significant packet loss in the evenings.


Just to be clear, I'm calling the Arris CM8200 the cable modem and then it's plugged in via Ethernet to the router.


Most (but not all) evenings, from around 7 - 8 pm, my connection speed drops from the usual 90+ Mbs down and 35+ Mbs up that I get as measured at to 15 - 20 Mbs down and 0 - 0.5 Mbs up. Yes, quite frequently the Telstra speedtest page is unable to even give me a figure on the upstream speed. Pings also go from sub 10 ms to anywhere between 30 - 150 ms.


Measuring packet loss by pinging reveals that when the speed issues start, there is significant (30 - 50%) packet loss on the connection. Power cycling the router or the cable modem has no effect on the connection.


The issue usually fixes itself after a number of hours, often by 10 - 11 pm it's better, although occasionally it persists through to the morning.


On one evening recently, the speeds improved after 11:30 pm but not back to normal full speeds, however there was still significant packet loss (10-20 %) until I power cycled the cable modem.


I had an nbn tech come out yesterday morning, however as the issue only occurs after 7pm, I clearly couldn't demonstrate it to him. He measured the signal strength and said it was up around +9dB and said it needed to be between -3dB and +3dB so he put a 6dB attenuator on the line. This hasn't made any difference to the issues in the evening.


Here's a graph of the connection to over the past 48 hours. The Packet Loss stats (PL% Column) is packet loss over the last 60 minutes. You'll see that it's a pretty solid connection.


The graph at the bottom shows the stats over the last 48 hours. The black line is the round-trip time to ping and the red bars are dropped packets.


The graph shows that between roughly 7 pm and 11 pm on the evening of the 8th I had some packet loss and the ping times increased slightly. The nbn connection was slow, but usable during this time.

On the evening of the 9th, there's massive amounts of packet loss for an extended period of time from about 9pm through until around 3 am. During this period, the internet was unusable. Pages timed out, email couldn't be sent and I couldn't watch streaming video.

Ping Plot for


Here's a more detailed view of the last 12 hours

Packet Loss over 12 hours to


During these times of packet loss, there is packet loss to every router in the path, and packet loss to - not just packet loss to one hop in the path. The packet loss graph is maxing out at 30% - during these issue periods, the packet loss is up around 50 - 60 % and the internet is completely unusable.

When I can get to actually load and respond, it's showing a very low download speed - 10 - 20 Mbs, but the upstream speed is often too low to measure, and when it can be measured it never exceeds 1 Mbs.


Oh, and I'm not at all worried about the two routers in the path with 100% packet loss - I am aware that this means they are not responding at all to ICMP packets and this is not indicative of a problem.


I'm also not overly concerned about the response times and very slight packet loss from the router - while it responds to ICMP ping requests, it's likely configured to do this at the lowest priority and again is not likely to indicate a problem.


Just in case it matters, I'm in Doncaster, Melbourne and we have just switched over to HFC nbn as soon as it became available in the last 2 months.


Prior to this I was on 100 Mbs Telstra Cable for over 6 years and experienced maybe one dropout for a few hours at a time no more than once a year (from memory only 4 significant dropouts over that time). Speeds were consistently solid between 75 - 100+ Mbs down and 2 - 2.5 Mbs up.

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Level 2: Rookie

Re: NBN on HFC - 100/40 plan with significant packet loss in the evening.

Oh, and one more thing - I have done a complete isolation test and plugged my computer into the Arris cable modem via Ethernet and the issue still persists. It is not something on my network. The issue affects all computers on my network, whether connected via Ethernet or Wifi.

Level 2: Rookie

Re: NBN on HFC - 100/40 plan with significant packet loss in the evening.

yes mate, I'm having exactly the same issue here and I called telstra and guess what the guy on the phone said: IT IS NOT TELSTRA'S CONCERN AND IT IS YOUR SOFTWARE ISSUES!

I just can't believe this


and I posted this issue on this forum and look at what the tech support from telstra said:
Please be aware that BigPond doesn't guarantee any set Pings times or Latency, so our Technical Support team will no be trained in this area nor will they be unable to help.  Have you considered setting up your modem with a DMZ mode?


Srsly? I just can't really believe what I've just read, I mean it is definitely up to them to bring us a stable and reliable Internet without any packet loss!

and I can't really believe I was told to try DMZ mode.... it just doesn't help at all....

Level 2: Rookie

Re: NBN on HFC - 100/40 plan with significant packet loss in the evening.

What a joke.

The ping times and latency are not the problem as such, they are symptoms of a larger problem - that I believe is lack of capacity on the upstream channel for the entire HFC cable network segment.


I think that after the congestion reaches a certain amount on the upstream channel (which is far more constrained for bandwidth than the downstream channel) that everything falls over and packets are dropped.


The issue is not slow ping times, or changes in the latency - the issue is the massive number of dropped packets. More than 50% packet loss is simply not acceptable.


I have logged my issue with Telstra on multiple occasions (fortunately they never tried to tell me a load of crap like they've told you) and I have escalated it to the TIO -


I would encourage you to log it with the TIO if you haven't already done so.

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