VPN Slowdown

  • ATTENTION! As of November 1, 2020, you are not able to reply to threads 6 months after the thread is opened if there are more than 500 posts in the thread.
    Threads will not be locked, so posts may still be edited by their authors.
    Just start a new thread on the topic to post if you get an error message when trying to reply to a thread.

Weggy

Regular Contributor
Hi,

I have a "RT-AC5300"

I run a VPN Client using Private Internet Access.

My "normal" WAN connection speed is 100 Mbps.

However, when utilising the VPN the connection is limited to 47Mbps and I'd like to figure out why this is the case. It's worth noting that the same connection on my NAS tops out at the expected 100Mbps. Does anyone know why this might be?

One theory I have but I can't be sure as I don't understand entirely how a VPN functions on a router and the stress it could create, is that the CPU is not fast enough to deal with the speed. The reason I think this is that when running two back to back speed tests on the VPN the CPU graph looks like this:
1634916419083.png


Perhaps my config is not setup correctly? Or perhaps I'm simply limited by the hardware.

If the hardware is the issue, is there better hardware I could use to get higher VPN speeds? Next week I'm due to get an upgrade to 900Mbps, which I'd like to utilise as much as possible using a VPN.

Many Thanks
 

ColinTaylor

Part of the Furniture
Yes you are CPU limited because of the encryption necessary for the VPN. ~50Mbps is about correct for the processor in your router. To get faster VPN throughput you would need a router that has support for hardware encryption, like the RT-AC86U or RT-AX86U.
 

Weggy

Regular Contributor
Okay, this next question is probably a silly one but... :)

What is the most powerful (and I guess therefore best) router Asuswrt-Merlin supports?
 

ColinTaylor

Part of the Furniture
Probably the RT-AX86U with its quad core 1800 MHz processor. Bear in mind that OpenVPN can only exploit one CPU core. With my RT-AX86U I get 250 Mbps with NordVPN before hitting the CPU limit.
 

Weggy

Regular Contributor
That's interesting and annoying at the same time :)

My NAS has a INTEL Celeron J3455 with a clock of 1.5GHz which doesn't appear to be much slower than the router I have with it's Broadcom BCM4709C0 @1.4GHz
 

eibgrad

Very Senior Member
That's interesting and annoying at the same time :)

My NAS has a INTEL Celeron J3455 with a clock of 1.5GHz which doesn't appear to be much slower than the router I have with it's Broadcom BCM4709C0 @1.4GHz

That's because the system architecture makes a significant difference too. Anything x86 based is going to make mincemeat of these consumer-grade routers, esp. when it comes to the VPNs, no matter how much they improve the processor speed. That's why the following beast is x86 based.


A couple years ago, I moved my OpenVPN client to a small form-factor PC I built from spare parts that were just collecting dust on the shelf. Motherboard is nothing special. In fact, pretty lame (only 1GHz, integrated processor), even by the standards of its day (circa 2011). But it absolutely blows away *any* consumer-grade router because it's x86 based.

So rather than constantly upgrading my router just for the sake of better VPN performance (I'm otherwise perfectly content w/ my ASUS RT-AC68U), I threw some parts together and handed responsibility for my OpenVPN client over to the PC (btw, it only consumes about 18 watts, so the additional cost of operation is still far less than the cost of having to upgrade the router).
 
Last edited:

Similar threads

Latest threads

Sign Up For SNBForums Daily Digest

Get an update of what's new every day delivered to your mailbox. Sign up here!
Top