SoftEther VPN User Forum

So my situation is that I am running a win 2019 Server with the following hardware/OS config:

• Quad core 3.2Ghz processor

• 16 Gigs of ram

• SSD drive

• Intel mainboard w integrated nic (integrated Intel NIC is used for VPN only)

• An additional NIC with dual ports added to the system, ports are NIC Teamed.

• System is fully updated

• Antivirus has been removed

• Windows Defender firewall is disabled on all networks.

• Workgroup Setting (no AD)

Internet is provided at 100x25
Speed tests from computers inside the network confirm the speeds and latency is at 10-20ms

Softether is configured as follows:

• 1 Hub

• Local bridge goes to the intel NIC with VLAN transparency enabled.

• NO layer 3 switches

• NO L2TP/IPSEC/SiteToSite options enabled

• NO MSTTP/OPENVPN options enabled

• DDNS and VPNAZURE enabled/configured

• NO VPNGATE

• NO SecureNAT

• UPD Acceleration disabled

• All other built in options are at defaults

The SoftEther Clients are mostly windows 10 using the softether client software and configured to use 16 connections, half duplex, no UDP Acceleration. They are connecting to the vpnazure address.
There is an Iphone and Ipad tablet, both using the SSTP Connect app and connecting only in SoftEther VPN mode also with 16 connections half duplex, no UDP Acceleration.

Variations in testing: Connections have been reduced to 8 with and without half duplex enabled. UDP Acceleration has been both enabled and disabled.
Nat-T in the client has been both enabled and disabled without any noticeable speed changes.

The Actual Issue
Regardless of the settings I am unable to get speeds through the VPN are around 2 Mb/s and latency at around 400ms steady.
Tests have been run from multiple computers at multiple locations using FTP client to pull and push large files to and from an FTP server inside the network.
The FTP server was tested from inside the LAN with the same files and provided the files at expected speeds for the LAN.

And at this point I'm looking for ideas or suggestions on what/where my bottleneck might be.

isaacG wrote: ↑

Wed Mar 30, 2022 3:54 pm

They are connecting to the vpnazure address...
I am unable to get speeds through the VPN are around 2 Mb/s and latency at around 400ms steady.
... what/where my bottleneck might be.

Your connections take a round trip via VPN Azure servers in Japan.

vpn azure is slow to users outside Japan and usually used only when the server can't be exposed to the Internet. Why can't you expose the server?

eddiewu wrote: ↑

Thu Mar 31, 2022 8:49 am

vpn azure is slow to users outside Japan and usually used only when the server can't be exposed to the Internet. Why can't you expose the server?

The documentation led me to believe that vpnazure was only used to establish the initial connection.

So I should be using the Dynamic DNS address instead of the VPNAzure address?

Yes generally you should.
What you said is true if udp acceleration is enabled and active. However that depends on your NAT type and may not work in some networks.
In softether client and sstp connect you can check if udp acceleration is active.

eddiewu wrote: ↑

Thu Mar 31, 2022 3:25 pm

Yes generally you should.
What you said is true if udp acceleration is enabled and active. However that depends on your NAT type and may not work in some networks.
In softether client and sstp connect you can check if udp acceleration is active.

I had UDP Accel off and NAT-T off. I've turned them on server side, and will test from clients over the next day.

isaacG wrote: ↑

Thu Mar 31, 2022 4:47 pm

eddiewu wrote: ↑

Thu Mar 31, 2022 3:25 pm

Yes generally you should.
What you said is true if udp acceleration is enabled and active. However that depends on your NAT type and may not work in some networks.
In softether client and sstp connect you can check if udp acceleration is active.

I had UDP Accel off and NAT-T off. I've turned them on server side, and will test from clients over the next day.

With Nat-T and UDP both turned back on the speed tests (using the vpn command line clients) are similar.


Total Average Throughput | 1,829,060 bps| 1.83 Mbps

Turned on does not mean it’s active.
You need to check the connection status. If the speed is unchanged, very likely it’s not active.

I enabled and watched the logs via sstp connect app and I do see quite a bit of UDP messages that lead me to beleive UDP is active.

At this point I'm looking at assigning a public ip to this box and trying a direct connection from outside to see how things go.

SSTP connect will show UDP sign next to Connected if udp is active. Softether client status will show UDP acceleration is active: Yes.

So going the direct route and just using the ddns path with ports open on the public side was the part of the puzzle I was missing. Now speeds and ping response times are "near native". So the problem is solved at this point.