Hi @chatswood What may be happening in your area is that the more customers that slowly connect to NBN will increase the traffic on a multicore trunk cable from your local pillar to the node.
What happens is that the increased traffic causes crosstalk, this lowers your SNR (signal to noise ratio) and throttles back your line rate to be more reliable at the expense of speed sometimes.
This will improve once everyone in your area gets off ADSL which is in co-existence on the same multicore cables. When ADSL is still enabled in an NBN area, the Node and DSLAM power levels are reduced to avoid interference and damage to and from other services such as ADSL and PSTN lines.
The reduction in power levels then in turn reduces your SNR and as a result the ability to connect at the best possible speed. You will also notice that your SNR will be slightly lower at peak times such as early evening as a result of the increased traffic.
It's still possible that you have a less than perfect connection to the node due to a failing joint somewhere, usually a remote line test will show that up but only if it's actually on the bad side of an intermittent cycle.
