Fun with openvpn: how to jam a line

After upgrading my internet connection from something like 50MBit/s download and 5MBit/s upload to 100Mbit/s download and 50Mbit/s upload, my openvpn connection to an external server became really slow. Before the upgrade, the answer of a ping came after about 40ms, after the upgrade it needed about 1000ms and from time to time even 10000ms. Yes, really 10s to get the reply though I did not change any openvpn configuration.

The solution: Never ever use TCP for an openvpn connection, always use UDP!

There are more options to tune the connection (like don’t use compression nowadays) but really do not use TCP!

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