Here are some settings to speed up the transmission rate through your OpenVPN tunnel:
mssfix: Even though MSS itself is a TCP feature, this OpenVPN option targets encapsulated UDP packets. It will change the MSS value of the TCP protocol inside the tunnel in such a way that after UDP encryption/encapsulation, the resulting UDP packet size (minus IP/UDP headers), will not exceed the
By setting the value to 0, we disable this feature.
fragment: This will disable OpenVPN’s internal fragmentation routines (OpenVPN 2.x actually does this by default).
Another improvement is raising the
MTU (Maximum Transmission Units), which is the maximum datagram size in bytes that can be sent unfragmented over a network path.
First make sure your OpenVPN server has set the same MTU size:
ip link set eth0 mtu 9000
Next, add this to your OpenVPN configuration: