SoftEther slow speeds?

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Dwebtron
Posts: 5
Joined: Sun Sep 30, 2018 1:42 pm

SoftEther slow speeds?

Post by Dwebtron » Sun Oct 14, 2018 5:00 am

I've been having some trouble with getting slower-then-expected speeds from my SoftEther server. The server is located over the internet about 20 miles away from where I'm testing, and is on a 1gbps network. My home network is around 200mbps. When I download a file over FTP from the exact same server as the VPN is hosted on, I get my full line speed. When I do it through the VPN, I get 1/10th or sometimes even less speed!

I've attached some screenshots of speed testing on and off of my VPN conection. The Android screenshots are using the SoftEther protocol, while the iOS screenshots are using L2TP. Similar results on both protocols, both on the same server from the same building on the same Wi-Fi.


What gives? What should I check? How can I fix this? Is this just how slow SoftEther is? I know it's not the latency or server (as far as I can tell...) since FTP and SSH works over my full line speed. Is there more information I can provide to help track this problem down?
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sky59
Posts: 119
Joined: Tue Sep 11, 2018 5:58 pm

Re: SoftEther slow speeds?

Post by sky59 » Sun Oct 14, 2018 6:07 am

you expect the same speed!?

you think crypting/decrypring needs no time?

I think you should celebrate with 30MBit, i have 2Mbit

Dwebtron
Posts: 5
Joined: Sun Sep 30, 2018 1:42 pm

Re: SoftEther slow speeds?

Post by Dwebtron » Sun Oct 14, 2018 9:47 pm

sky59 wrote:
Sun Oct 14, 2018 6:07 am
you expect the same speed!?

you think crypting/decrypring needs no time?

I think you should celebrate with 30MBit, i have 2Mbit

Yes. The CPU on the server tops out around 30-50% when I test. That's a single-core CPU with 1GB of ram. I just tried a 6-core CPU with 16 GB of ram (both are 1gbps) and the result is mostly unchanged. I believe it's not the encryption that's the bottleneck. I also tried a 4-core CPU w/ 2GB of ram physically located on my local network, and STILL had significantly worse speeds. The local machine was 1 hop away from my test machine. I got approximately 20-25% of the line speed. The CPU usage never went above 20%.

HTTPS transfers from these servers go at full line speed, which are also encrypted. I'm reasonably certain it's not the encryption/decryption, and it's something with SoftEther. Especially because of documentation like this: https://www.softether.org/1-features/4. ... gh_Ability

Are the other VPN protocols THAT SLOW that Softether's "fast" is still 20% of line speed? Why is this so, if it's not the CPU? What else can I do to improve this?

cmd wh0ami
Posts: 125
Joined: Sun Jul 16, 2017 6:58 pm

Re: SoftEther slow speeds?

Post by cmd wh0ami » Mon Oct 15, 2018 10:31 am

If you didn't test this out on so many different CPU's I would suggest maybe its the bug with the newer 4.15.0-36 kernels that started including the fix for the Intel spectre issue. I've been hearing there's a major issue with network performance regression from the patch. I know someone saying their getting as much as 66% performance reduction on network throughput.

I highly doubt this is your issue, but I figured I'd throw this up here for others who search for an answer... Here is a link to a logged bug against Linux from the kernel update.

https://bugs.launchpad.net/ubuntu/+sour ... ug/1796895
VPN Discord invite: https://discord.gg/QByKXA9

thisjun
Posts: 2348
Joined: Mon Feb 24, 2014 11:03 am

Re: SoftEther slow speeds?

Post by thisjun » Thu Oct 25, 2018 6:06 am

Could you show your configuration of VPN?
Did you use SecureNAT? If so, some SecureNAT mode is slow.

Dwebtron
Posts: 5
Joined: Sun Sep 30, 2018 1:42 pm

Re: SoftEther slow speeds?

Post by Dwebtron » Fri Apr 26, 2019 1:35 am

I'm sorry to take so long to reply to this, but I'm still having trouble. I tried it on AMD CPUs that wouldn't have the Intel spectre fix, the latest version of Ubuntu with the latest version of SoftEther (I just tried again today) and even tried on LAN and still am getting 10-20% of my line speed over 1gbps connection.

I've tried disabling SecureNAT and using a bridge instead. It seemed like the initial connection was faster, but instead of 10-20% speed reduction I seem to go even slower - 5-10% (the range depends from multiple tests)!

I again tried upping it from 1 CPU / 512MB of ram to 4CPU/2GB of RAM, and no difference. Although, it does seem like the SoftEther code scales well, but neither CPU configuration went over 30% usage during testing.

My configuration file as request is attached as a .txt because ".config" files aren't allowed by the forum.

Do you want me to add any log files? I just created a new VM today to run the tests - I can do it again and provide any case / scenario you need to speed this up. Right now the Ubuntu machine is running on a VM inside of a Windows 10 box. My other configurations are on cloud VPS providers like DigitalOcean/Vultr/Azure/etc and they all exhibit the same behavior.
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