RT-AC68U as AiMesh node cuts half LAN speed

Oleksandr

New Around Here
Hi All.
I have two devices AiMesh setup with stock firmware (upgraded to the latest version) - AX88U as the main router and AC68U as a node. There is wired connection between them.
The device connected to the main router shows ~920 Mbits/sec in iperf3 test.
The same device connected to the node shows ~460 Mbits/sec.

Tried different options: node reset, whole system reset, disabled QoS, disabled Jumbo Frame, disabled firewall and AiProtection - did not help.
As temporary (I believe) solution I am using the cheapest 1Gb switch from aliexpress for wired connections (gives me ~900 Mbits/sec) and AC68U plugged-in to this switch for wireless connections only.

Thank you for any help.
 

L&LD

Part of the Furniture
Welcome to the forums @Oleksandr.

How are you running the iperf3 tests? What is the device on the other end and how is it connected?

Have you tried a new Ethernet cable between the two routers and between the node and the testing device?

If you're using a mobile device to do the iperf3 testing with, is it plugged into AC power at both testing locations?

How methodical were you when testing after doing a full reset on your network? Maybe the following may help you see what you may improve when doing a full reset.

Fully Reset Router and Network
 

follower

Very Senior Member
Hi All.
I have two devices AiMesh setup with stock firmware (upgraded to the latest version) - AX88U as the main router and AC68U as a node. There is wired connection between them.
The device connected to the main router shows ~920 Mbits/sec in iperf3 test.
The same device connected to the node shows ~460 Mbits/sec.

Tried different options: node reset, whole system reset, disabled QoS, disabled Jumbo Frame, disabled firewall and AiProtection - did not help.
As temporary (I believe) solution I am using the cheapest 1Gb switch from aliexpress for wired connections (gives me ~900 Mbits/sec) and AC68U plugged-in to this switch for wireless connections only.

Thank you for any help.
UTP Cable or RJ45 Plug issue. Cheap cables and RJ45 make this kind of issue a lot.
 

Oleksandr

New Around Here
Welcome to the forums @Oleksandr.

How are you running the iperf3 tests? What is the device on the other end and how is it connected?

Have you tried a new Ethernet cable between the two routers and between the node and the testing device?

If you're using a mobile device to do the iperf3 testing with, is it plugged into AC power at both testing locations?

How methodical were you when testing after doing a full reset on your network? Maybe the following may help you see what you may improve when doing a full reset.

Fully Reset Router and Network
Hello L&LD.
The iperf3 server is running on Asustor device which connected to the main router with two cables and link aggregation enabled (tried without link aggregation and one cable - the result is the same).
Of course I tried to use manufactured short cables and got the same result. Also I tried different new cable between main router and node - no difference. Wifi tests gives similar speed ~400 mbits/sec on node and ~700 mbits/sec when connected to main router (the device supports AX). Resets I did with buttons on the routers.
 

Oleksandr

New Around Here
UTP Cable or RJ45 Plug issue. Cheap cables and RJ45 make this kind of issue a lot.
Hello follower.
Cables were the first think I checked. Also there were tests using short cables from routers and NAS packages.
As I mentioned as a temporary solution I am using Mercusys MS105G switch connected to the main router and then to the device. The also node connected to the same switch for WiFi clients only.
This setup shows (same cable):
[ ID] Interval Transfer Bandwidth
[ 4] 0.00-10.00 sec 1.08 GBytes 930 Mbits/sec sender
[ 4] 0.00-10.00 sec 1.08 GBytes 930 Mbits/sec receiver

The same I am expecting to get without switch. But it gives:
[ ID] Interval Transfer Bandwidth
[ 4] 0.00-10.00 sec 566 MBytes 474 Mbits/sec sender
[ 4] 0.00-10.00 sec 566 MBytes 474 Mbits/sec receiver
 

Oleksandr

New Around Here
Have received CAT6 patch cords to test the hypothesis that my CAT5e wires are not working correctly. Also upgraded the node to 3.0.0.4.386_43137. Tried several resets of node and then main router and node. The issue still there - the LAN and AC WiFi speed is ~400 Mbits/sec. Now I am confident that my wires are fine.
Continue using the switch between nodes and devices to have 1Gb LAN (0.5Gb for WiFi is fine).
Please let me know if anyone has any other suggestion to try. Thanks.
 

L&LD

Part of the Furniture

pypk

Occasional Visitor
I have the same problem. I have 3 RT-AC68U. One is a router and the other 2 are AiMesh nodes. I have the latest firmware on all three units: 3.0.0.4.386_43137. All three were factory reset and then NVRAM erased (using the WPS button method). Both nodes are connected via Ethernet. I have eliminated wiring as the problem because if I take the wire that is going into the node and directly connect to my laptop, I get a 980mbps transfer rate. If I connect it through the node, then I get 600mbps.

I strongly suspect this is a firmware issue. The only difference between now and before the problem, that I can think of, is the firmware update.
 

L&LD

Part of the Furniture
I suggest you haven't taken 'that specific cable' out of the possible issues. It isn't just the actual wire inside, it is the interconnects on both ends that matter too (they may be marginal when connected to the router.

Use a brand new/different manufacturer/Brand cable to really mark that possible issue 'put to bed'.

Right now, we know that node, cable, and laptop combination doesn't work. You need to test for that exact setup again (with a new cable).
 

pypk

Occasional Visitor
I tested with a number of cables, a brand new Cat 6 and a Cat 7 cable both 6 feet in length and the nodes are still showing half speed. I also tested the other node with the same method (router to the node to laptop) and it's the same problem. All at half speed. Just to mention, it is the exact same speed ~600mbps. If the cable is the problem, I would think that varying cables will yield different speeds.
 

MDMower

New Around Here

L&LD

Part of the Furniture
Yes, that post above yours from almost 12 hours ago helped to confirm that.
 

pypk

Occasional Visitor
So it looks like this problem started months and two firmware releases ago. I'm curious if Asus knows about this and intent to fix it.
 

pypk

Occasional Visitor
Yes, I reported the same problem here: https://www.snbforums.com/threads/rt-ac68u-firmware-version-3-0-0-4-386-43129.72638/post-705234 (and credit to @master_o_trunks who reported it well before me).

This started with firmware version 3.0.0.4.386.43129. I switched to Merlin 386.3 and my node lets traffic run at ~900Mbps again. It's unfortunate that Asus hasn't noticed this during their QA cycle of two releases now.

@L&LD - this really is a firmware issue, not a hardware issue.

Hi MDMower. A little help, please. I switch my router to Merlin 386.3_2 and left my nodes on stock firmware 3.0.0.4.386_43137. I'm still getting only 600Mbps. Can you let me know if you are on 386.3_0 and I should do that? Or did you switch all your nodes to Merlin as well in order to get 900Mbps back?
 

pypk

Occasional Visitor
Well, answered my own question. In case anyone is wondering, I had to install Merlin 386.3_2 on the nodes as well to get the speed back. Now all is well, back to 900+Mbps.
 

shoman94

Regular Contributor
I had a similar issue with my AC88u an it was fixed with the most recent firmware that was just released.
 

Oleksandr

New Around Here
Hello all. Today tried to do the factory reset as L&LD recommended, because previously I did it with reset button.
And the issue is still there. I have never tried Merlin firmware - the official were fine for me until this case.

Does anyone know how to raise a ticket for Asus? Seems they ignore messages from Feedback page.
 

Sumanji

New Around Here
Hi All,

I am experiencing this bug also, on the latest official firmwares available:
  • RT-AX86U running as main router (FW: 3.0.0.4.386_45934)
  • RT-AC68W running as AiMesh node on Ethernet backhaul (FW: 3.0.0.4.386_45987)
Connecting my desktop via an Ethernet cable directly to the AX86U I get full speed on my FiOS connection (roughly 940Mbps both up and down). If I connect that same cable to the AC68W, then connect my PC to the node, I only get ~460Mbps each way - i.e., half.

Seems like the Merlin firmware fixes this, but I don't want to move off the official firmware. Will post back if a subsequent update happens to fix this... until then I am doing the same as Oleksandr and using a cheap switch to connect the wired clients directly to the main router.

Cheers,

Su
 

ForkWNY

Regular Contributor
The 68U definitely has throughput issues on the latest firmware releases, I can confirm this behavior as well. Bandwidth seems capped at 450-480Mbps for any WIRED clients connected directly to the 68U when it is set up as an AiMesh node.
 

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