I always has an 100Mbit/s connection from my ISP. This always worked well with AirVPN I got about 92Mbit/s with this VPN.
Some days ago I got a 200Mbit/s connection from my ISP and the VPN speeds dropped to about 60Mbit/s and sometimes lower.
I tried several VPN and also different protocols. Even stunnel didn't fixed the problem.
I often read about changing the MTU size or the mssfix value to 1300. This did not the Job for me.
My solution was the TCP Optimizer.
This tool can just be executed and must not be installed. It should be run in Administrator Mode.
(Right click on the exe file -> run as administrator)
Step 1 adjust your connection speed
Step 2 select your network adapter
Step 3 Click on MTU/Latency
Step 4 Click on largest MTU
[do this once when you are connected to the VPN and once outside the VPN]
In VPN I got a result of maximum MTU 1300 and outside I had 1500.
Please share your results and your connection speed.
Step 5 Back to general settings
At the bottom choose "custom" set MTU to the calculated value and "apply changes".
Even after the changes not all AirVPN servers worked well for me. I will create a list with servers who worked with my options.
Please report your results if this helped you.
This list is not complete:
List of Server with 200Mbit/s
List of Servers with slow speeds