VPN Speed and Temp Difference between 384.x and 386.x

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ASadani

Senior Member
Hi Everyone; Over the past few weeks, I have been trying to figure out the reason for my VPN Connection speed drop and have been working with my provider to get to the root cause of it.

Problem Statement: My VPN used to clock over 220 Mbps over VPN while I was on 384.x and recently, I couldn't get over 130-140 Mbps.

My setup is the combination of two routers of AC86U. (Primary and Node). I have since downgraded the firmware of both my primary router and the node to 384.19 (The last 384 Firmware) and my VPN Speeds are back to 220 Mbps+

The CPU Temps have reduced from 95°C to 77°C as was the case earlier

So far I am going to stick with 384.19. I wonder if anyone else has seen this discrepancy with their setup?

PS: I have other friends who have seen the speed reduction with the firmware updates as well and all of them are on the AC86U
 

dave14305

Part of the Furniture
See :
If your temperature gets too high, a CPU might get disabled and potentially result in a drop in VPN performance.
 

ASadani

Senior Member
See :
If your temperature gets too high, a CPU might get disabled and potentially result in a drop in VPN performance.
The router is just fine with the higher CPU. Except for the VPN Speeds. Reverting back to 384, brings back the temps and increases the VPN by 60 Mbps which is a good difference
 

dave14305

Part of the Furniture
The router is just fine with the higher CPU. Except for the VPN Speeds. Reverting back to 384, brings back the temps and increases the VPN by 60 Mbps which is a good difference
VPN requires CPU-intensive encryption and decryption on the router. One affects the other.
 

ASadani

Senior Member
VPN requires CPU-intensive encryption and decryption on the router. One affects the other.
During Speedtest, the CPU temps don't go higher but the speed is stuck at the slower speeds. It may be the case, though I'm unsure but wanted to report this finding specifically
 

tobifr34k

Occasional Visitor
Same Problem with VPN Speed with any firmware higher than 384.19 with my RT-AC86U, but i have no problems with higher temperatures. Look here:


Who is your vpn provider?
 

primitivo

Senior Member
I have the same issue. Mine provider is Astrill. Honestly because of this issue I have stopped using Asus and Merlin altogether (sorry @RMerlin , I guess it is not your fault).

@tobifr34k I read the other thread, I would not attribute the speed decrease to be related to OpenVPN version. The reason why is because both myself and the OP are using Astrill applet on AC86U which comes with tweaked and optimized version of OpenVPN based on 2.3 version and has not been touched (modified) since years. Astrill is installing with the applet its own OVPN version which is used with their RouterPro protocol.

This is clearly some FW related issue but my expertise is too shallow to tell what is the root cause of this issue, we only know since when it happened.
 

ASadani

Senior Member
Same Problem with VPN Speed with any firmware higher than 384.19 with my RT-AC86U, but i have no problems with higher temperatures. Look here:


Who is your vpn provider?
Mine is Astrill
 

Sky1111

Senior Member
VPN performance degradation is not related to thermal throttling. I am running VPN with AX86u with faster CPU + cooling, and with temperature only 62c, my VPN is ~100-120 (and this is on 1Gbps connection)
 

RMerlin

Asuswrt-Merlin dev
VPN performance degradation is not related to thermal throttling. I am running VPN with AX86u with faster CPU + cooling, and with temperature only 62c, my VPN is ~100-120 (and this is on 1Gbps connection)
I ran a speedtest with NordVPN and my RT-AX88U a few days ago, and I was able to hit 220 Mbps, which was the CPU limit. I recommend you check your settings.
 

primitivo

Senior Member
I ran a speedtest with NordVPN and my RT-AX88U a few days ago, and I was able to hit 220 Mbps, which was the CPU limit. I recommend you check your settings.
AC88U is unaffected with this @ASadani can confirm I guess as he has both AC86U and AC88U. Perhaps the same issue is with AX86U and not AX88U.
 

RMerlin

Asuswrt-Merlin dev
Try using UDP instead of TCP. I just got 280 Mbps when using UDP on an RT-AX86U, but speed tanked to 20 Mbps when using TCP.
 

ASadani

Senior Member
AC88U is unaffected with this @ASadani can confirm I guess as he has both AC86U and AC88U. Perhaps the same issue is with AX86U and not AX88U.

This is specific to the AC86U. I have tried this with the AX88U and the speed remains at 200+Mbps. The reduction occurs with the AC86U in my setup.

Now I've since the beginning I have found the AX88U to be an unstable router. I probably may have received a defective unit as I can't believe Asus will create such a buggy product. The AX band rarely connects. The VPN drops packets. Hence I reverted back to the trusted AC86U
 

ASadani

Senior Member
Try using UDP instead of TCP. I just got 280 Mbps when using UDP on an RT-AX86U, but speed tanked to 20 Mbps when using TCP.
I am using UDP Pro on the Astrill Applet. If I revert back to plain UDP, the speed reduces to 50Mbps. If I use TCP, the speed does go down to about 40 Mbps.

It's a clean Factory Reset and the firmware install. There are no setting modifications that are done. I have downgraded both the primary AC86u and the node AC86u.
 

ASadani

Senior Member
I ran a speedtest with NordVPN and my RT-AX88U a few days ago, and I was able to hit 220 Mbps, which was the CPU limit. I recommend you check your settings.

In my tests with the AX, I can achieve over 200 Mbps on the speed tests. That is correct. However, with the AX88u I do have packet drops on the voice calls constantly.
 

primitivo

Senior Member
Try using UDP instead of TCP. I just got 280 Mbps when using UDP on an RT-AX86U, but speed tanked to 20 Mbps when using TCP.
I appreciate your feedback and input and I have also donated for your excellent work, but I would also appreciate not making noobs of us users using VPN 24/7. I may not be present on this forum as I used to be but I do remember the nicknames and without going into details I remember user @Sky1111 to be always active in some VPN threads. I also remember that you @RMerlin have helped few years back with sorting out the installation of the Astrill applet after some modifications have been done to the FW, which prevented its installation.

In terms of setup myself and the op had pretty much the same over the years. We are both running Astrill applet and both using RouterPro UDP protocol which is based on the same version of modified OpenVPN (2.3.x) and we have measured against the same servers and from different ISPs.

Because of this significant VPN performance drop on AC86U from 240Mbps to 140Mbps I have switched to R9000 + Wireguard and get now 500Mbps. While I still like Asus FW more and would not mind still using AC86U with 240Mbps VPN performance, I can't agree on using outdated firmware as my main WAN router, while the 386 FWs cannot reach more than 140Mbps.
 

Kingp1n

Very Senior Member
I appreciate your feedback and input and I have also donated for your excellent work, but I would also appreciate not making noobs of us users using VPN 24/7. I may not be present on this forum as I used to be but I do remember the nicknames and without going into details I remember user @Sky1111 to be always active in some VPN threads. I also remember that you @RMerlin have helped few years back with sorting out the installation of the Astrill applet after some modifications have been done to the FW, which prevented its installation.

In terms of setup myself and the op had pretty much the same over the years. We are both running Astrill applet and both using RouterPro UDP protocol which is based on the same version of modified OpenVPN (2.3.x) and we have measured against the same servers and from different ISPs.

Because of this significant VPN performance drop on AC86U from 240Mbps to 140Mbps I have switched to R9000 + Wireguard and get now 500Mbps. While I still like Asus FW more and would not mind still using AC86U with 240Mbps VPN performance, I can't agree on using outdated firmware as my main WAN router, while the 386 FWs cannot reach more than 140Mbps.
I use a full time VPN and only get 40 mbps. No issues at all while streaming. Of course I don't pay much for speeds haha. I would be perfectly fine hitting 140 mbps in a heartbeat. Best of luck!
 

Sky1111

Senior Member
Both routers are running Merlin 386.2-6, the cable modem is in a bridge mode, so no double NAT.

Here is what I get from ISP:
1624453031037.png

(and this is with kids in online classes)

and here is what I get on VPN:
1624452947774.png

(maximum ever clocked on VPN: 130 Mbps

I am using UDP, and here are my VPN settings - please advise if there is anything that can be adjusted:
1624453183137.png
 

Makaveli

Very Senior Member
In my tests with the AX, I can achieve over 200 Mbps on the speed tests. That is correct. However, with the AX88u I do have packet drops on the voice calls constantly.

I believe you got a defective unit with your ax88u I haven't seen those issues with mine over the course of the last 3 years that i've owned it.
 
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