Performance Issue

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Posts: 2
Joined: Thu Nov 22, 2018 4:37 am

Performance Issue

Post by ingmar » Sun Dec 16, 2018 1:07 pm

Hi all,

I have set up a more complex VPN Setup between three main locations and five branch offices. In this setup I have massive performance drops from about 4.5 MByte to about 100kbyte, when transfering data via the VPN in comparison to direct conncetion via intertnet (I used wget to test).

The Setup is as follows:
Main Office A / DSL 100/40 Mbit (
Main Office B / DSL 100/40 Mbit (
Main Office C / Cable 400/40 Mbit (

In all locations Softether is installed on dedicated AMD APU2D4 Boards, aes-ni is enabled and working, running on Ubuntu 18.04LTS (I also tried with 16.04LTS). I recompiled Softether 4.28 to be sure, the last libssl binary is included and used for AES-NI.
Connection encryption is set to "AES-256", top shows me about 15-20% CPU Usage during tests.
Connection is done using 32 parallel TCP connections (UDP was even slower).

I have set up the VPN Servers behind a NAT firewall, which is forwarding all required ports. So only one nic is used and bridged to the local hub.
As I have the server installed in all three locations, I have set up Layer3 Switching and established dedicated Networks in a separate IP Range ( which are assigend as virtual network adapters to each hub. Reason for this was, that I do not have one centralized instance, where all remote offices connect to. Routing itself works fine between the networks.

In the branch offices, I have set up the same setup on APU2D2 Boards, but also there, the performance via VPN is not acceptable.

I checked the packet and the security logs without identifying any issues.
SecureNAT is disabled in all locations.

Any help, how to identify, what is going wrong, is highly appreciated.

Best Regards

Posts: 31
Joined: Tue Aug 28, 2018 6:44 am

Re: Performance Issue

Post by davidebeatrici » Mon Dec 17, 2018 7:18 pm


Could you try to compile the latest development version available on GitHub ( and check whether the issue persists, please?

Best regards,

Posts: 2
Joined: Thu Nov 22, 2018 4:37 am

Re: Performance Issue

Post by ingmar » Thu Dec 20, 2018 8:45 pm

Hi Davide,

thanks for your reply.
I have recompiled with the last git version, but this made things even worse.
Now I get packet drops and ssl disconnects from the clients frequently:

Code: Select all

2018-12-20 21:27:14.543 On the TCP Listener (Port 5555), a Client (IP address XXX.XXX.XXX.XXX, Host name "", Port number 57460) has connected.
2018-12-20 21:27:14.543 For the client (IP address: XXX.XXX.XXX.XXX, host name: "", port number: 57460), connection "CID-4" has been created.
2018-12-20 21:27:14.614 SSL communication for connection "CID-4" has been started. The encryption algorithm name is "AES256-SHA".
2018-12-20 21:27:14.705 [HUB "XXX"] The connection "CID-4" (IP address: XXX.XXX.XXX.XXX, Host name:, Port number: 57460, Client name: "SoftEther VPN Server (Cascade Mode)", Version: 4.20, Build: 9608) is attempting to connect to the Virtual Hub. The auth type provided is "Password authentication" and the user name is "site-2-site-from-xxx".
2018-12-20 21:27:14.705 [HUB "XXX"] Connection "CID-4": Successfully authenticated as user "site-2-site-from-xxx".
2018-12-20 21:27:14.705 [HUB "XXX"] Connection "CID-4": The new session "SID-SITE-2-SITE-FROM-XXX-3" has been created. (IP address: XXX.XXX.XXX.XXX, Port number: 57460, Physical underlying protocol: "Standard TCP/IP (IPv4)")
2018-12-20 21:27:14.705 [HUB "XXX"] Session "SID-SITE-2-SITE-FROM-XXX-3": The parameter has been set. Max number of TCP connections: 32, Use of encryption: Yes, Use of compression: No, Use of Half duplex communication: No, Timeout: 20 seconds.
2018-12-20 21:27:14.715 [HUB "XXX"] Session "SID-SITE-2-SITE-FROM-XXX-3": VPN Client details: (Client product name: "SoftEther VPN Server (Cascade Mode)", Client version: 420, Client build number: 9608, Server product name: "SoftEther VPN Server Developer Edition (64 bit) (Open Source)", Server version: 51, Server build number: 9666, Client OS name: "Linux", Client OS version: "Unknown Linux Version", Client product ID: "--", Client host name: "vpn-gateway", Client IP address: "", Client port number: 57460, Server host name: "", Server IP address: "yyy.yyy.yyy.yyy", Server port number: 5555, Proxy host name: "", Proxy IP address: "", Proxy port number: 0, Virtual Hub name: "XXX", Client unique ID: "BF1F4622F86FF3B226E0A6EE1D350E7E")
2018-12-20 21:27:14.872 Connection "CID-4" has been terminated.

Code: Select all

2018-12-20 21:27:15.978 For the client (IP address:XXX.XXX.XXX.XXX, host name: "", port number: 57462), connection "CID-7" has been created.
2018-12-20 21:27:16.059 SSL communication for connection "CID-7" has been started. The encryption algorithm name is "AES256-SHA".
2018-12-20 21:27:16.140 Connection "CID-7" has been terminated.
Is this an issue between the different versions of Softether?

Best Regards

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