SoftEther VPN User Forum

Hello,
I've installed VPN Server on Ubuntu.
VPN clients: iphone, Windows 8

Network Traffic Speed Test Tool:
without VPN:

Average Throughput in Download Direction | 36,882,029 bps| 36.88 Mbps
Average Throughput in Upload Direction | 4,933,468 bps| 4.93 Mbps

with VPN (L2TP or SSTP or SoftEteher VPN client with Local Bridge or SecureNAT):
Average Throughput in Download Direction | 300,533 bps| 300.53 Kbps
Average Throughput in Upload Direction | 4,792,693 bps| 4.79 Mbps


from VPN server to another server:
Average Throughput in Download Direction | 950,715,379 bps| 0.95 Gbps
Average Throughput in Upload Direction | 921,468,146 bps| 0.92 Gbps

CPU usage max 2%
Any ideas why download is so slow?

from another server to VPN server via VPN:

Average Throughput in Download Direction | 9,140,777 bps| 9.14 Mbps
Average Throughput in Upload Direction | 905,329,447 bps| 905.33 Mbps

At the same time dstat:

----total-cpu-usage---- -net/total- ---paging-- ---system--
usr sys idl wai hiq siq| recv send| in out | int csw
0 0 100 0 0 0| 0 0 | 0 0 |5686 12k
0 0 99 0 0 0| 597B 1631B| 0 0 | 366 710
0 0 99 0 0 0|6306B 6897B| 0 0 | 514 1242
0 0 99 0 0 0| 13k 14k| 0 0 | 656 1815
6 4 87 0 0 3| 85M 84M| 0 0 |5201 34k
6 4 88 0 0 2| 117M 116M| 0 0 |4836 47k
7 5 86 0 0 3| 114M 114M| 0 0 |5567 45k
6 5 87 0 0 3| 110M 110M| 0 0 |5589 46k
6 3 88 0 0 3| 114M 114M| 0 0 |4772 47k
6 4 87 0 0 2| 114M 114M| 0 0 |5274 47k
6 5 87 0 0 2| 117M 116M| 0 0 |5063 47k
6 5 87 0 0 2| 114M 113M| 0 0 |6064 48k
6 4 87 0 0 2| 114M 114M| 0 0 |5473 44k
6 4 88 0 0 2| 111M 111M| 0 0 |5026 46k
6 5 86 0 0 2| 117M 117M| 0 0 |5187 46k
6 4 88 0 0 2| 117M 116M| 0 0 |4672 48k
6 5 87 0 0 3| 112M 112M| 0 0 |5200 45k
7 5 86 0 0 2| 112M 111M| 0 0 |6414 44k
7 5 87 0 0 2| 117M 116M| 0 0 |4924 48k
2 2 95 0 0 1| 36M 36M| 0 0 |1927 17k

I've made separate tests for upload/download between servers via VPN:

only download

Average Throughput in Download Direction | 88,183,112 bps| 88.18 Mbps
Average Throughput in Upload Direction | 0 bps| 0 bps


only upload

Average Throughput in Download Direction | 0 bps| 0 bps
Average Throughput in Upload Direction | 910,387,042 bps| 0.91 Gbps

Why "Average Throughput in Download Direction" is very low still ?

**deleted** incorrect statement... download is always very low, compare to upload and non-VPN download

VPN Server ---- VPN Client

TrafficServer ---- TrafficClient - download ~88Mbps
TrafficClient ---- TrafficServer - upload ~ 8 Mbps

Why?

I've removed Local Bridge on VPN Server.
Then tested connection between VPN clinets: client1<->VPN Server<->client2

Upload and Download were maximum.
So, the problem is with LocalBridge?!

<zeropitarr>

What are you using as your traffic load between client and server?

What CPU is your server running?

I ask because I could not get that kind of speed running on very up to date hardware, details at:

http://www.vpnusers.com/viewtopic.php?f=7&t=7270

-----
Test 1: "vpnserver" and "vpnbridge" are Quad core i7-6700K @ 4.00 GHz on each end and with 1 GigE NIC hardware and 1 GigE switch. It appears I can max the tunnel out at ~850/850 Mbps bidirectional throughput. It does not appear to matter at all how many TCP sessions are active.
-----

Q:What are you using as your traffic load between client and server?
A: traffic tool in vpncmd

Q:What CPU is your server running?
A:Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz

...I could not get that kind of speed running on very up to date hardware...
A: I was able to get 0.95Gbps for upload only. Download is terrible


UPDATE:

I was able to achieve UP & DOWN :300-500Mbps by removing Local Bridge and enabling SecureNAT with DisableKernelModeSecureNAT = true.
CPU usage is very high as result =(

Any ideas how to fix Local Bridge ?

No, apologies. :(

The async nature of your problem has me scratching my head.

For my traffic load I used the vpncmd tool as well as iperf on other dedicated machines.

iperf_machine----vpnSERVER----vpnBRIDGE----iperf_machine

When I started hammering the connection (iperf client and server on both iperf_machines pointed at each other, up and down, multiple streams) the CPU on both the vpnserver and vpnbridge spiked to 1 core at basically 100%.

I then moved the test to lesser hardware but more cores and throughput dropped to <500 Mbps, but it was always synchronous / even up and down, regardless of final throughput.

[scratches head]

I am even questioning the 0.95 Gbps upload as I could not get that on the bench with equal hardware.

Is "compression" enable anywhere? Compression killed my throughput testing down into the ~125 Mbps range.

I've found a solution.

I switched to Local Bridge with TAP. (I was using bridge with eth0)

Congratulations, I am glad you found a solution.

What OS are you on?

Thank you!

ubuntu 16.0.4.1 amd64

Thanks, same.

I know this is an old topic, however, I found myself having the same problem and I was scratching my head for a while until realized that my VPS had a funny MTU value of 1986 for eth0 so I changed it to the standard 1500, then I also needed to change the value of MTU on SecureNAT to 1280, only then it worked at perfect speed.

Hope this helps someone else!

A. Nakayama

Hello, I have exactly the same situation. Tried to change MTU size to 1280 and gretap0 MTU size to 1500. No improvement. Any suggestion is welcome here. Thanks

old threat, but also struggled with this problem.

On my setup, a "double-bridge" setup helped.
I configured SoftEthers local bridge to create a new TAP (named vpn --> linux inerfacename tap_vpn) device (and NOT to bridge to eth0/eno0/whatever).
And with linux system tools, I create a bridge containing eth0 and tap_vpn.

On ubuntu 22.04, I just installed bridge-utils and use this netplan:
Nice sideeffect. The SoftEther-IP (in my case 192.168.178.140 is now reachable through VPN too)