Our company has 3 VPN Servers in US. We want to monitor network performance ( the most important factor is how fast users from different locations in the world can download data when using our servers ). Is there any service or application for this purpose?
I would write a script that tests this and deploy it on multiple locations world-wide (rent out a small VPS or spin up EC2-instances when needed).
Make sure the script has one of three outcomes:
You can add some additional info after that.
You could then install Icinga (Nagios fork) and use check_nrpe to run the test-script you wrote from the icinga-server on specific intervals and report back to Icinga. This would give you a nice overview of how all off the servers are doing from different locations in one dashboard.
This works for both Windows & Linux.