Slow performance on VPN with kong dd-wrt 31520M

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athedrummaster's picture
Slow performance on VPN with kong dd-wrt 31520M

Let me start by saying that I am new to VPN and DD-WRT. That being said, i have followed many tutorials and tried lots of fixes. Using (I know, not as reliable), without openvpn I get 135 Mbps download and 21 Mbps upload. When I enable openvpn, my speed drops to about 27 Mbps down and 10 up. I use PIA as my vpn service and have tried many different servers. I have port 1198 128-AES CBC encryption cypher and SHA1 as my hash algorithm. I am using,, and as my static DNS. Any suggestions?

bgram's picture
Similar situation, without

Similar situation, without openvpn I get 110/6mpbs and with PIA goes down to 25/6mbps. I did not notice much change in upload but download drop drastically.

-> R6900 flash to dd wrt Kong 31575 by updating boardid. 

killerdevildog's picture
im having same problem i get

im having same problem i get about 27/18 but i have ATT Giga power(1gbps/1gbps). Tried using tomato and DD-WRT. Also several diffrent VPNS.

FuShiLu's picture
Well you'all did something

Well you'all did something wriong or the VPN info your using is crap. I have a VPN running 24/7, the VPN is getting close to 80% of available speeds and the systems outside the VPN are getting 95% of the speeds expected. Currently I have 100/10 from TekSavvy and the current VPN is through STrongVPN, but I also switch it up through IronSocketVPN and XpressVPN so I'm confident its your settings. Two years back I went through 10 of the reported top providers and most of the top were not that great. Anyhoo I kept accounts with these threee each has a feature or two I like for certain things.

That said, OP, if those are the settings being provided by the sevice, give them a call. If they are not, whay are you using them? If you give StrongVPN at least a test, they have a feature where you can just run a script under Admin>Commands and it will set everything for you. If that works you can make decsions. I usually recommend thi approach for most people as they don't require deep details.

I only run a few systems through the vpn, te rest go through my ISP, do make sure you put in Policy Base Roting under your VPN tab the following.


This ensures the ssytems you set here (one per line) will go through the VPN and the VPN shutsdown any traffic if the connection breaks.wink wink


richie225's picture
So when you add these routes:

So when you add these routes:


So you add a route for every device on your network or only the devices you want to route through the VPN? As in, anything you don't place here, uses the normal ISP connection? or anything you don't place here can't see past the internal network?

Para Dox
Para Dox's picture
I think you will find that

I think you will find that the performance degradation is largely due to the OpenVPN encryption\decryption impact on the router’s CPU.

On a 100Mbps ISP connection:

My PC going through my router (R7000, Kong build) connection clocks 90Mbps with OpenVPN disabled, and 42Mbps with OpenVPN enabled.

My Samsung Galaxy Tab S2 with an Android OpenVPN client installed gets and even a bigger OpenVPN performance hit because its CPU is less powerful.

My HTC One XL smartphone with an Android OpenVPN client installed has an even bigger performance hit yet again because it has the least powerful CPU.

If you Google ‘Open VPN performance test’ you will find some testers that  had 50%+ performance hit.

stefanneacsu's picture
I have a R7000 with DD-WRT

I have a R7000 with DD-WRT Kong build on it, running 24/7 VPN connection to Nord VPN, using OpenVPN. My ISP connection speed (no VPN), is 50Mbps. With VPN turned on, connection speed is the same. I have also tested the CPU capabilities of the R7000, by saturating the download bandwidth for about 10-15 mins (basically I turned on the VPN and started a large file download from a HTTPS server) and the CPU load monitor on the status page never went above 27% load.

stefanneacsu's picture
Forgot to mention that during

Forgot to mention that during the testing, the download speed stayed constantly at max.