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OpenVPN slow on ASUS Quad-Core CPU

IPbasher

Occasional Visitor
Hello Guys,

I have an Asus RT-AX56U with 1.5 Quad-Core-CPU (BCM6755). I have installed the newest Merlin Software on it.

I am using PIA VPN as my VPN Provider. But still i get only 60-70Mbps on OpenVPN with UDP port 1198 with AES-128-CBC+SHA1.

With UDP port 1197 with AES-256-CBC+SHA256 i am also getting the 60-70mbps.

With L2TP i get the full speed of my ISP(100Mbps)

What can be optimised? Doesnt the Router have AES-NI? I bought the Router because i thought that the Router as enough CPU Power.

I used following commands:
explicit-exit-notify 2
ifconfig-nowarn
tls-client
persist-key
persist-remote-ip
remote-cert-tls server
auth-nocache
fast-io
sndbuf 524288
rcvbuf 524288


Are there any other Commands in order to make the OpenVPN Connection faster?
 

RMerlin

Asuswrt-Merlin dev
No, the RT-AX56U does not have AES acceleration.
 

CaptainSTX

Part of the Furniture
Probably as good as it is going to get. Open VPN is a single core process so try and run your VPN clients on the core not being used by the router. Not sure how Merlin has it setup on a quad core but on a dual core router the router's primary function is on core 1 so I run my VPN clients on core 2.
 

L&LD

Part of the Furniture
For faster VPN performance on the router itself, either the RT-AC86U or the RT-AX88U will be required (and both support RMerlin firmware, of course). :)
 

L&LD

Part of the Furniture
Sure, lots of tweaks and combinations possible. None will be a significant increase over the speeds you're seeing now though. :)
 

RMerlin

Asuswrt-Merlin dev
Any Optimazation can be done? Or is 70Mbps the Max out of this Router?
Not much you can do if you only control the client side of it. If your server supports NCP, then ensure that AES-128-GCM has priority over AES-256-GCM.
 

IPbasher

Occasional Visitor
On my AC86 I normally get 200 - 230 Mbps on a VPN tunnel. While the WAN tests at 220 - 240.

I have heard of speeds approaching 250 Mbps on an AC86 using OpenVPN.
Thats the Case when AES Ni is enabled. But i mean when it isnt activated and encryption runs on one Core only.

Or maybe examples of other Asus Routers without AES Ni.

What was the Maximum Speed there?
 

CaptainSTX

Part of the Furniture
Thats the Case when AES Ni is enabled. But i mean when it isnt activated and encryption runs on one Core only.

Or maybe examples of other Asus Routers without AES Ni.

What was the Maximum Speed there?
AES-NI is built into the chip's architecture. I'm not aware of any way to disable it.

As for the speeds on other routers without AES-NI my dual core AC1900P can do 60 Mbps downloads on Open VPN. Other posters report similar speeds with over clocked AC68s.

The key to speed on Open VPN is a processor that incorporates AES-NI.
 

Marin

Very Senior Member

CaptainSTX

Part of the Furniture
Which one is the cheapest Asus Router which has AES NI and Merlin Support?
Be careful if you decide to try and save money and buy a used or refurbished AC86. Some of the AC86s manufactured in 2018 were very problematic and unreliable.
 

IPbasher

Occasional Visitor
I think i will Stay on my RX-AC56U. Primary use is just to have an other ip adress to stream... And stabile Connection without Drops. Not heavy Downloads.

Are there any overclock Options for encryption?
 

IPbasher

Occasional Visitor
Are there other Reports from Users who get more then 80Mbps without AES NI? :)

Maybe with the Same Router or similar cpu power
 

K-2SO

Very Senior Member
I think i will Stay on my RX-AC56U
60-70Mbps out of your 100Mbps ISP is good. With RT-AC86U you'll get ~90Mbps with your ISP. Is it worth it?

Are there other Reports from Users who get more then 80Mbps without AES NI? :)
I've seen >250Mbps. Depends on many factors. VPN server, encryption, time of day, etc. Usually 180-220Mbps with my VPN.
 

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