OpenVPN slow CPU usage Low

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guyman70718
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Joined: 16 Apr 2018
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PostPosted: Mon Jul 26, 2021 0:05    Post subject: OpenVPN slow CPU usage Low Reply with quote
I'm trying to use OpenVPN with my Netgear r6400v2 and although it is working, the speeds are about 40mbps when I am able to get over 100mpbs by connecting to the vpn from my computer directly. I understand that this can be caused by low end router CPUs but the CPU usage on my router isn't even reaching 20% usage. I did notice however that the CPU idles around 63 C, and was wondering if it was possible that it was thermally throttling?

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kernel-panic69
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Joined: 08 May 2018
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Location: Texas, USA

PostPosted: Mon Jul 26, 2021 2:12    Post subject: Reply with quote
Or, it could be that you are using the "latest" build from the router database, which isn't updated...

https://download1.dd-wrt.com/dd-wrtv2/downloads/betas/

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guyman70718
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Joined: 16 Apr 2018
Posts: 4

PostPosted: Mon Jul 26, 2021 3:28    Post subject: Reply with quote
kernel-panic69 wrote:
Or, it could be that you are using the "latest" build from the router database, which isn't updated...

https://download1.dd-wrt.com/dd-wrtv2/downloads/betas/


I installed build 47086 and I still have the same issue.
kernel-panic69
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Joined: 08 May 2018
Posts: 10100
Location: Texas, USA

PostPosted: Mon Jul 26, 2021 4:50    Post subject: Reply with quote
What is your ISP plan upload/download speeds? I wouldn't suspect a config issue if it is connecting to your VPN provider, but that is a possibility as well. Would probably need more details about your config and environment to troubleshoot.
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DON'T use Chromium-based browsersRTFM/STFW TL;DR is NOT an excuse. • Why Should I Care What Color the Bikeshed Is?
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guyman70718
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Joined: 16 Apr 2018
Posts: 4

PostPosted: Mon Jul 26, 2021 4:56    Post subject: Reply with quote
kernel-panic69 wrote:
What is your ISP plan upload/download speeds? I wouldn't suspect a config issue if it is connecting to your VPN provider, but that is a possibility as well. Would probably need more details about your config and environment to troubleshoot.

I pay for 100/100, and I usually get a bit more (around 110/110). The part that confuses me is that the speeds I get are a bit random. Normally I can get around 35/35 using the VPN but after playing with settings I am able to get like 20/80 or 40/60. Sometimes its as asymmetrical as 0.1/80 It's confusing since the only way I can make these changes is to just change a few settings back and forth, which I think is restarting OpenVPN? Even if I could tip it to be 80/20, I would be happy. VPN provider is AirVPN but I played a bit with Nord as well.


Edit: I read through the OpenVPN Log and I see
Code:
20210726 07:35:19 W WARNING: 'link-mtu' is used inconsistently local='link-mtu 1535' remote='link-mtu 1558'
but when I add link-mtu to the additional config OpenVPN wont start anymore.
Alozaros
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Joined: 16 Nov 2015
Posts: 4521
Location: UK, London, just across the river..

PostPosted: Mon Jul 26, 2021 7:26    Post subject: Reply with quote
VPN speed depends on many things...
-router CPU (R7000 & R6400v2 have the same CPU max VPN is 30-40Mbit)
-encryption used - try chachapoly if it is supported by your VPN provider (its the fastest) or 128 or 256 GCM
-servers speed that could be delivered, some servers at some point are overused and tend to slow down
-servers location, access points and ect.

_________________
Atheros
TP-Link WR740Nv1 ---DD-WRT 47117 BS AP,NAT
TP-Link WR1043NDv2 -DD-WRT 47474 BS AP,NAT,AP Isolation,Ad-Block,Firewall,Local DNS,Forced DNS,DoT,VPN,VLAN
TP-Link WR1043NDv2 -DD-WRT 47381 BS AP,NAT,Ad-Block,Firewall,Local DNS,Forced DNS,DoT,VPN,VLAN
TP-Link WR1043NDv2 -Gargoyle OS 1.12.0 AP,NAT,QoS,Quotas
Qualcomm Atheros/
Netgear R7800 --DD-WRT 47381 BS AP,NAT,AD-Block,AP&Net Isolation,VLAN's,Firewall,Local DNS,DoT,Vanilla
Netgear R9000 --DD-WRT 47474 BS AP,NAT,AD-Block,AP Isolation,Firewall,Local DNS,DoT,2,4Ghz only,Vanilla
Broadcom
Netgear R7000 ---DD-WRT 47381 BS AP,Wi-Fi OFF,NAT,AD-Block,Firewall,Local DNS,Forced DNS,VLAN's,DoT,VPN
------------------------------------------------------
Stubby for DNS over TLS I DNSCrypt v2 by mac913
egc
DD-WRT Guru


Joined: 18 Mar 2014
Posts: 8159
Location: Netherlands

PostPosted: Mon Jul 26, 2021 8:36    Post subject: Reply with quote
40Mb/s is normal for these routers running OpenVPN.

R7800 does about 85 Mb/s

ChachaPoly is a bit faster but usually not supported by commercial providers as they use AES.

Fastest to commercial providers is AES-128-GCM but we are still talking of speeds around 40 Mb/s

Use WireGuard which is about 3 times faster Smile

Links about OpenVPN and WireGuard are stickies in the Advanced Networking forum also in my signature

_________________
Routers:Netgear R7800, R6400v1, R6400v2, Linksys EA8500, EA6900 (XvortexCFE), E2000 (converted WRT320N), WRT54GS v1.
WireGuard Documents & Guides:https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=327397
OpenVPN Documents & Guides: https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=327398
IPSET: https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=327261
Install guide R6400v2:http://forum.dd-wrt.com/phpBB2/viewtopic.php?t=316399
Install guide R7800: https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=320614
Forum Guide Lines (important read):https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=324087
guyman70718
DD-WRT Novice


Joined: 16 Apr 2018
Posts: 4

PostPosted: Mon Jul 26, 2021 14:10    Post subject: Reply with quote
egc wrote:
40Mb/s is normal for these routers running OpenVPN.

R7800 does about 85 Mb/s

ChachaPoly is a bit faster but usually not supported by commercial providers as they use AES.


I am using Chachapoly since my provider does support it but my current provider does not support WireGuard. I am between providers right now though so I will keep my eyes out for a WireGuard provider that fits my needs.


However, I don't fully buy that this router cannot do any more than 40Mb/s. I just turned the router back on this morning, and although just last night before going to sleep I was getting a max of about 30-35Mb/s, I just did a test and I got 50/110 on the same router with the same settings. I did notice the CPU is much cooler, which makes sense considering it has been off for over 8 hours. I am really starting to believe that it is a cooling issue, and I will be doing some testing with cooling mods to make sure.
Alozaros
DD-WRT Guru


Joined: 16 Nov 2015
Posts: 4521
Location: UK, London, just across the river..

PostPosted: Mon Jul 26, 2021 17:08    Post subject: Reply with quote
Wireguard speed is ok, but OpenVPN offers some options and better configuration...

the only chance this R6400v2 to get more than 40Mbit is if your VPN was down...

you can overclock it a bit or use a cooling tricks, but still it has a Broadcom dual core CPU at 1ghz and that's all it can do...in fact, im open for any tricks to learn, how you can squeeze those speeds you expect... Rolling Eyes

_________________
Atheros
TP-Link WR740Nv1 ---DD-WRT 47117 BS AP,NAT
TP-Link WR1043NDv2 -DD-WRT 47474 BS AP,NAT,AP Isolation,Ad-Block,Firewall,Local DNS,Forced DNS,DoT,VPN,VLAN
TP-Link WR1043NDv2 -DD-WRT 47381 BS AP,NAT,Ad-Block,Firewall,Local DNS,Forced DNS,DoT,VPN,VLAN
TP-Link WR1043NDv2 -Gargoyle OS 1.12.0 AP,NAT,QoS,Quotas
Qualcomm Atheros/
Netgear R7800 --DD-WRT 47381 BS AP,NAT,AD-Block,AP&Net Isolation,VLAN's,Firewall,Local DNS,DoT,Vanilla
Netgear R9000 --DD-WRT 47474 BS AP,NAT,AD-Block,AP Isolation,Firewall,Local DNS,DoT,2,4Ghz only,Vanilla
Broadcom
Netgear R7000 ---DD-WRT 47381 BS AP,Wi-Fi OFF,NAT,AD-Block,Firewall,Local DNS,Forced DNS,VLAN's,DoT,VPN
------------------------------------------------------
Stubby for DNS over TLS I DNSCrypt v2 by mac913
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