How to change MTU settings

In case you have speed problems a slight change in your MTU settings might do the trick. MTU is the Maximum Transfer Unit, the biggest package a client can send to a certain server. Per default it's 1.500 byte - which already might be a bit too much, because your DSL connection adds another 8 byte. Then two packages need to be send: one with 1.500 byte and one with 8 byte. This either slows down your connection or even blocks it completely (for some low cost equipment simply hangs then).

To change your MTU settings, please proceed as follows (depending on your Windows OS the steps might differ a bit):

  • Open the Windows Control Panel
  • Switch 'View' to 'Small symbols'
  • Click on 'Network and Sharing Center'
  • Click on the connection to be changed, which is 'LAN connection' (CyberGhost must have been started for this)
  • Click on 'Properties'
  • Click on 'Configure' and activate the 'Advanced' tab.
  • Highlight 'MTU' and change the settings to '1300'
  • Click on 'OK' and leave the network settings.

CyberGhost usually uses a value of '1.300', but this is under certain circumstances not the best value for your respective provider. In  that case you should adjust the setting accordingly.

To find out the best value for your provider you need to know his IP address. Then you can open a command line and ping that address:

  • Click on 'Start' and type in the search box 'cmd'.
  • Double click on the search result
  • Under Windows 8 open an Explorer window, click on 'File > Open a command prompt > Command prompt'
  • Type in  'ping -f -l 1300' (address of your provider)
  • Now repeat with a higher value:  'ping -f -l 1310'
  • Repeat again with the next higher value:  'ping -f -l 1320'
  • Repeat and increase the value again and again ...
  • ... until the answer says: 'Package should be fragmented'. The last value without this answer plus '28' (which should be added for the ping itself needed '28' while working) is the optimal MTU setting.

In this example it's '1460', while '1480' is too much:

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