How to measure internet speed with VPN

[RL600]

I am currently connected via an VPN.
When I use speedtest.net to test my internetspeed it gives back wrong speeds.
I tested with all other devices off or not using internet so that can not be the answer.
My internet is 200 mbit/s up and down.
Sometimes it is measuring 600 mbit/s or just 120 mbits/s.

How can I measure my internet speed with VPN?

 

[Rayven2]

I'd say perhaps you have browsers open or that downloads but the speed shouldn't drop by that much.

However if you do see a increase in speed using a VPN that's because your ISP normally throttles the speed and it can actually increase dramatically (Even 3x more).