Suppose you run a website and you are getting reports from your customers in a particular office that your website has suddenly become very slow. But it's perfectly fast everywhere you test it from, so you suspect the problem is at their end - for example their network connection, their firewall, or their web browser configuration.
Is there a way to measure the speed problems they are seeing, perhaps by adding some javascript to your website to record some metrics?
I'd run smokeping on a VM or recycled Linux box behind their firewall to get a good idea of what their bandwidth looks like over time. Maybe it is only slow during the day or when they're doing updates or something. But you need at least a few days of minute-by-minute stats to get a good baseline and to start picking out irregularities.
If you can get packets and bytes in/out from the firewall and graph that in Prometheus or datadog or the metrics system of your choosing that's helpful too. But seeing what real ping and http response time are is more representative of what your end users are dealing with so I'd start gathering that first.
