Given optimal conditions your VPN speed might nearly reach the speed of your physical Internet connection. However, certain additional factors can also have a negative impact:
- If your physical Internet connection is limited to e.g. 768 kBit/s, then your VPN speed can't be any faster.
- Sometimes technical problems might force your VPN speed to slow down, e.g. a server breaks down, the CyberGhost service is having technical difficulties or the service needs to be worked upon. We apologize for any inconvenience!
- High peaks (e. g. in times many users connect, such as weekends or Friday nights) can lead to capacity problems, equivalent to streaming services, which then usually lower video resolutions to avoid servers collapsing.
- The length and quality of the connection between you, the VPN exit server and the target address.
- In other cases the distance between your location and the CyberGhost server you are logged into might be very long. For example if you were living in Romania and you connected to one of our US servers there are approx. 4 times x 8.000 km that information has to travel, so unavoidably some speed loss will occur.
- Your provider slows down encrypted connections.
- There is a routing problem between your provider and the server used (usually this comes and goes which makes it difficult to handle).
- CyberGhost's OpenVPN configuration is not compatible with your Internet connection (different packet sizes). If that's the case, there should be the same problem on all servers and at all times.
- Speed losses may also occur, when:
- A server is utilized by too many users.
- Encryption slows down a server (this goes especially for small devices such as routers, where CPUs might get totally occupied by encrypting)
- A network tool on your system slows down your VPN connection.
The 'VPN Process'
When using a VPN connection, all data is divided into packets before being sent. These data packets are then encrypted with AES-256 bit. This is a complex and computationally intensive step. After the encryption, more control information is set before the data (Header), so due to additional information every packet is bigger as it originally was. This so-called “Overhead” is proportionally bigger, the more small packages are sent, since the control information have a fixed size regardless of the size of the original packets. For example, at CyberGhost (via OpenVPN) this takes approximately 50 bytes per packet (it varies depending on the setting for encryption, authentication etc.).
For example: a 1 MB file which is sent into 874 packets has 874*50 Byte additional data (Overhead), which must be transmitted, so 43700 Byte. This means 5%. If 1 MB file is sent into 2097 packets, then 2097*50 Byte additional data (Overhead) must be transmitted, so 123723 Byte. This means approx. 12% Overhead.
The size of the data packets depends among others on the following aspects: over which servers are these sent and which packets size does the remote station accepts (MTU).
At the measurement of speed tests with active VPN connection is measured only how many user data can be transmitted over a period of time, therefore the above-mentioned Overhead is not measured.
So when using a VPN, more data must be transmitted. Through the encryption this lasts even longer, depending on the processor load of the PC. When you are surfing on the Internet over a CyberGhost server, you are not the only one using this, which means that this server must receive a lot of packets, to encrypt/decrypt and forward.
A server on which are connected for example 50 persons and each of them wants to download with 50 Mbit/s, must be able to handle at least 2,4 Gbit/s user data. But the TCP/IP protocol used on the Internet adds another “Overhead”,so in practice, the measurements have shown that a 1 Gbit fastened server reaches approx. 580 Mbit/s net bandwidth (user data bandwidth). Therefore in order to transmit 2,4 Gbit/s user data, the server must be equipped with a 5 Gbit connection. Such servers are hardly available, usually the regular servers offer only 1 Gbit connections. If we would decrease too much the number of simultaneously users per server, this would no longer be financially viable on one hand, and on the other hand the anonymity level would have to suffer.
OK, this all sounds nice, but I don’t even reach a fraction of my normal speed
In rare cases, an overload or an attack on one of our servers may massively affect the speed. In this case it simply helps to choose another server.
But I have lousy speeds on all servers!
Firstly it’s important to define „lousy“. Should you reach on all servers speeds less than 4 Mbit, although your Internet connection can do far more (you can test this on speedtest.net), you may assume then there is a problem on your PC. To check this, please test the VPN connection with sufficiently different servers at different locations (at least 3). If the results are all over bad, it means there is a problem on your PC.
OK, assuming the problem exists on my side. Which could it be?
Very often the problem could be traced back to some installed software, e.g. the existence or the remains of anti-virus programs, firewalls or other network utilities. We couldn't find out yet why these problems so far occur only during a VPN connection. Often responsible for these problems are “Filter Drivers”. These “Filter Drivers” are rooted programs in the system that monitor or tap the network traffic. In the best case, these are Firewall or anti-virus products that monitor the network traffic and in the worst case, Trojans and viruses.
In order to check if such a driver is active on your network card, please follow these steps:
- Close a possible existing VPN connection
- Open Control Panel\Network and Internet\Network Connections and right-click on the network connection and then on "Properties".
- Perform this for both the normal network connection as well as for the connection of the "TAP-Win32 Adapter V9"
You will see a list with check-boxes, which normally contains the following entries:
- Client for Microsoft Networks
- QoS- Packet Scheduler
- File and Printer Sharing for Microsoft-Networks
- Internet protocol Version 6
- Internet protocol Version 4
- I/O driver for Link Layer Topology Identification
- Answer for Link Layer Topology Identification
If there are more entries here, you can deactivate these for testing purpose, by removing the check-mark in front of the entry. Close the Properties window. Establish then a VPN connection and perform a speed test.
Other known causes are network configuration tools, which are often pre-installed on a PC (e. g. from Asus).
Here a list with tools, which cause problems (we will try to expand this list):
- Driver for D-Link WLAN sticks (works as a filter driver in your network adapter)
- Asus AI Suite
- CFOS Speed