That's just the short answer. The long answer is these routers use cheap ARM SoCs that don't compute very fast and lack AES acceleration so naturally they have mediocre OpenVPN performance. OpenVPN generally uses AES and its implementations don't tend to have good multi-threading support so now you're limited to VPNing with one core of your slow ARM SoC. If your VPN provider supports it (I can't tell), you can try downgrading the cipher from AES-256-GCM to AES-128-GCM which should result in some speedup. Popular consensus is that 128-bit key sizes are still good enough for AES so use your own judgement if you want to do this.
NordVPN seems to support the Wireguard protocol which uses much faster elliptical curve ciphers. 68U uses an ancient Linux kernel so it doesn't have good WG support. But if somehow manage to get it to work please write about it I'm interested too.
If you're bored and have too much free time you can probably roll your own solution with faster hardware. Or you can upgrade your router to a different model. Newer RT-AC86Us have AES acceleration.
I get about 30-40 mbits both ways on the AC68U, 1200 MHz CPU 800 MHz memory with AES-256-GCM, no compression algorithm. If you're interested in overclocking the router I wrote a post about it here:
https://www.snbforums.com/threads/r...13-is-now-available.57860/page-21#post-510501
It will only set the overclocks on successful reboots. If you run into power loss or software failure the overclock might not set and you'll revert to stock speeds until reboot, this is generally good.
I use the OpenVPN client feature to route mobile devices and to selectively enforce routing on certain sites with hardcoded IP voodoo magic. I think that's the best use case, nobody does anything bandwidth-heavy on phones/tablets. You'll save battery and sanity by not running OpenVPN on mobile devices.
Based on
@ironclad's helpful posting many months ago,
https://www.snbforums.com/threads/r...13-is-now-available.57860/page-21#post-510501, I have consistantly been running my ASUS RT-68U O/C'ed at 1200Mhz (Default clock was 800Mhz on my model--
(CFE) 1.0.2.0) with absolutely no problem for months.
Since I'm getting Covid-bored at home and bouncing off the walls, I decided to actually do some personal testing/pushing the envelope on my old router.
Actual testing on 04-24-2020 on dslreports.com speedtest:
Asus RT-AC68U--External USB drive on USB3.0--Small 1 1/2" USB fan on USB2.0 attached with scotch tape to the outside, one side back vent.
Using NordVPN as VPN client.
Note: Is the power supply the true limiting factor on how much you can O/C the router? (Thinking of the Raspberry Pi 4 power issues-- the more you juice up the O/C on it, the more overvoltage you gotta do--a weak power supply will cause it to fail) I did notice while running the router O/C'ed to 1400Mhz that the Asus branded power supply was a bit warm to the touch. But didn't think to touch it before the O/C, could be running warm to the touch all the time.
megabit/s dL/uL Overall/BufferBloat/Quality
@800Mhz CPU Frequency: CPU temp 60-61C bogoMIPS 15xx.xx (x2)
5.89d/2.29u C/C/C
15.45d/4.75u B/C/A
16.63d/5.14u B/C/C
@1200Mhz CPU Frequency: CPU temp 63-64C bogoMIPS 23xx.xx (x2)
20.31d/4.93u A/C/A+
17.94d/3.37u B/C/A
22.65d/4.82u B/C/A
@1400Mhz CPU Frequency: CPU temp 65-66C bogoMIPS 2798.38 (x2)
20.21d/4.94u A/C/A+
25.1d/5.06u B/C/A
25.1d/5.06u A/C/A+
(Been running for almost an hour and a half, O/C'ed and running 2xCPU's at 100%(using "while true; do openssl speed aes-256-cbc -multi 2 ; done" in ssh session--still running stable)
Edit: @1400Mhz CPU Frequency using Brave/Firefox browsers the speeds on DSLreports.com
are much better now:
megabit/s dL/uL Overall/BufferBloat/Quality
Firefox:
32.6d/5.16u B/C/B
Brave:
31.2d/4.47u B/C/A
(I guess mileage varies by so many factors, Time of day, Network Traffic etc)
Edit: @1600Mhz The router failed to boot. Couldn't access the GUI nor the ssh. All router lights except the 2.4Ghz and 5.Ghz Wireless came on.
Per
@Asad Ali's post from March 19, 2019,
https://www.snbforums.com/threads/b...eta-is-now-available.55520/page-9#post-473141 :
...the process for manually clearing the NVRAM:
1- Power off the Router.
2- Press and hold down the WPS button.
3- While holding the WPS button, plug in the power cable to turn router on.
4- Keep holding the WPS button for 30 seconds before releasing. The router should reboot.
5- It's Done!!
That worked. And since I followed ironclad's insistence to backup, backup,backup ... I restored both the Router settings and the JFFS partition.
The router returned to 1200Mhz CPU. I boosted it back to 1400Mhz CPU. If it fails at this speed in the future I will post an additional update.
