AC-88U OpenVPN & Overclocking Issue

[Kim Puleston]

Hey all,

I am new and glad to be here. Let me give a brief description of my issue.

I have an RT-AC88U Router that is setup in Wireless Router Mode. My RT-AC88U connects to my ISP router via the WAN port, so it is in a LAN-WAN configuration. I am currently running Merlin 380.62 Beta 1.

My issue is that when I use OpenVPN with an Overclocked CPU and RAM, my router really struggles and both cores on the CPU show massive usage even when there is nothing happening. I ran a Speedtest while connected to the VPN and my speeds are massively limited (5Meg Down). Now if I am to do the same WITHOUT the OC, everything seems to run just fine and I get my anticipated bandwidths (Between 30-40 Meg Down)

I have seen a few people running 1600 Core and 800 Mem on my model of router, as such I gave that a go, I have since lowered the OC (1500 Core 700 Mem)to see if I was reaching to0 high but for whatever reason, when overclocked and using OpenVPN everything goes mad. If I disable VPN then the CPU returns to the standard 5% usage when Overlocked which is what I would expect.

Just so its known the OC was done through SSH using the below commands as usual :

nvram set clkfreq=1500,700
nvram commit && reboot

Please note that this also happend on the previous Merlin release of 380.61 so its not an inherent issue to the latest Beta version.

Any ideas at all ?

Thanks in advance.

 

[john9527]

You can no longer overclock just by issuing the nvram commands (it will be reverted on a reboot). Some people have reported success using scripts that you can find in other threads..

Not withstanding the above, you cannot just pick any overclock values. Only certain values are recognized by the firmware. The values you are using are not valid, and will result in a clock setting of 800,533.

Valid CPU clocks are 600,800,1000,1200,1400,1600
Valid Memory clocks are 333,389,400,533,666,775,800

 

[Kim Puleston]

Thanks for the information. I will take a look and see if I can find the scripts. If anyone has a quick link though that would be handy.

As for the Overclocking Values, thanks for letting me know. However it does not resolve the situation I am facing with crazy things happening when using OpenVPN.

 

[Kim Puleston]

As a side note I am wondering if NAT acceleration does not play well with OpenVPN, I will test this tomorrow and give an update.

 

[RMerlin]

An RT-AC88U should have no problem reaching 60-70 Mbps with OpenVPN when using AES-128-CBC. If your results are lower, you might want to revise the cipher you are using - AES-256-CBC or higher are overkill for a home user, and the various Blowfish ciphers aren't optimized for that CPU.

Trying to overclock with unsupported values can cause the router to downgrade to the lowest clock rate it supports, which could be well below the default 1400 MHz clock (I remember observing something similar a few years back).

 

[hggomes]

Overclocking RT-AC88U will end up in disastrous results:

Stock:

Processor : ARMv7 Processor rev 0 (v7l)
processor : 0
BogoMIPS : 2798.38

processor : 1
BogoMIPS : 2798.38

Overclocked:

Processor : ARMv7 Processor rev 0 (v7l)
processor : 0
BogoMIPS : 199.06

processor : 1
BogoMIPS : 199.47


So basically 14x slower...

Give a try on and compare the results:

# openssl speed aes-128-cbc

 

[Kim Puleston]

Hmmm So after some more testing with NAT off and NO VPN I am running into issues using OC speeds of 1600,800.

I just ran a speed test and both cores were between 50/70% usage which is crazy. On Stock clocks I use like 5% much of the time when speedtesting. It is as if Overclocking this model yeilds worse results which I know can happen but seems odd I cant push it to 1600 without there being a huge performance hit.