pfSense

The idea isn't to use a speedtest.net to monitor actual bandwidth, but to monitor ping latency to see if the dummynet is catching the traffic. So if the pipe is full, but less than what the dummynet is set at (due to peak hour traffic congestion slowdown) then latency would increase beyond a set value.
When the latency increases beyond the threshold, then pfSense would automatically decrease the available bandwidth by X amount for X period of time - and continue to monitor, if latency is still above the threshold X time later, then decrease more.
After the ping reduces beneath the threshold, it allows the bandwidth to increase by X amount, monitors, and if ping remains within threshold, continues to allow increase in bandwidth and steps back up to the max value set in dummynet. If ping latency at some point goes beyond the threshold then it steps down the bandwidth again.
Basically bracketing bandwidth based on latency.

In my case, if i set dummynet limits below my current bandwidth, and monitor ping latency while filling the pipe it stays very low and is very consistent.
If I increase dummynet limits above what my bandwidth is, monitor ping and fill the pipe then latency rapidly goes into the hundreds and fluctuates but remains at a large value.
So, it is very apparent when dummynet is not catching my traffic by watching ping latency.

Preferably using a number of user-defined ping targets to increase reliability.

Other routers do use this method to adjust bandwidth successfully, and it doesn't cost much bandwidth to do so.

Please see this post: https://forum.pfsense.org/index.php?topic=137239.msg750900#msg750900

Actually, it seems completely possible. Van Jacobson’s “pathchar” showed so 20 years ago.

https://www.caida.org/tools/utilities/others/pathchar/pathcharnotes.html

Thanks Jim!

I really think this would be a highlight feature for pfSense.

It would be very effective traffic shaping for many home and small business scenarios that is also easy to configure. That's no small feature.

Thanks Jim(s) ;)

A bounty has been created for this project to be completed and submitted to be added to pfSense.

https://forum.pfsense.org/index.php?topic=137469.0