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Accepted
Degot
Asked: 2017-02-16 01:26:00 +0800 CST

SoftEther VPN has very slow download, while upload is high

  • 772

I've installed SoftEther VPN Server on Ubuntu 16.0.4.1

VPN clients: iPhone, Windows 8 and another Ubuntu Server

Network Traffic Speed Test Tool:

without VPN:

  • Download - 36.88 Mbps
  • Upload - 4.93 Mbps

with VPN (L2TP or SSTP or SoftEteher VPN client with Local Bridge or SecureNAT):

  • Download - 300.53 Kbps
  • Upload - 4.79 Mbps

from VPN server to another server without VPN (same LAN, 1Gbps):

  • Download - 0.95 Gbps
  • Upload - 0.92 Gbps

from another server to VPN server via VPN:

  • Download - 9.14 Mbps

  • Upload - 905.33 Mbps

  • Download -only - 88.18 Mbps

  • Upload -only - 0.91 Gbps

Why Download is very low ?

vpn ubuntu softether

3 Answers

  1. Best Answer

    There was a problem with Local Bridge (eth0), so I changed it to Local Bridge(tap) + br0(tap + eth0) => issue is fixed

    • 2

  2. This is how I did it (ubuntu 18.04/20.04):

    (1) Set up a bridge (br0) using netplan config and add the NIC interface only to the bridge (in /etc/netplan).

    (2) Add tap_softether to the bridge in start up script (in /etc/init.d).

    brctl addif br0 tap_softether # adding tap device after it's up.

    (3) Results: Download on openvpn went up from 1 Mbps (on physical bridge) to 100 Mbps (on tap bridge).

    • 2

  3. Had a similar issue. Hopefully my experience helps someone. I had a bridge br0 with several NICs, softether connecting to br0 using a veth pair (veth_se-veth_sebr) to avoid using dedicated NIC and still be able ping server. on a 100MB down, 10MB up I was seening 0.5Mdown/6MB up.

    I turned off TSO on both ends of veth.

    • ethtool -K veth_sebr tso off
    • ethtool -K veth_se tso off

    download speed now 80MBs, upload 6MBs

    • 0