Hardwired speeds suddenly halved- RT-AX86U

[HH22]

RT-AX86U behind 1 Gbps service. It's been rock solid forever, pulling 900+ down and up consistently. I noticed, however, my hardwired speeds- both up and down- have mysteriously dipped to <500 Mbps and I can't figure out what might be causing the problem.

The Internet provider was out today and confirmed speeds to the house- and in front of the router- are 900+. I watched the speed tests being performed. However, it was confirmed behind the router the speeds are, in fact, similarly diminished and nearly identical to what I am seeing via two desktop machines that are hardwired but behind switches (so a bad switch and/or cable could be ruled out as the culprit).

Would appreciate areas to explore- perhaps firmware settings, etc.- that I could experiment with before going nuclear and completely resetting the Asus router and starting fresh. I'm running what I believe to be the latest firmware (3.0.0.4.388.24231) and haven't seen reports that it causes such a huge impact to hardwired speeds.

Thanks in advance for the thoughts and direction.

 

[PureSpeed]

Have you tried Merlin‘s latest release for the AX86U? 3.0.0.4.388.5 is the latest and also a beta release is available for it.

 

[HH22]

Have you tried Merlin‘s latest release for the AX86U? 3.0.0.4.388.5 is the latest and also a beta release is available for it.

I haven't but at this point should probably give it a shot. Can one install over existing Asus factory firmware or is a reset required before installation?

 

[PureSpeed]

You can install over stock firmware you can dirty flash it without resetting it.

 

[HH22]

Thanks. Just installed the Merlin version. It's up and running and look forward to seeing the additional capabilities it brings. Unfortunately, the reduced hardwired speeds behind the router still exist.

Just wondering if I could have changed a setting within the firmware in the spirit of optimizing that could have caused such a dramatic and consistent decrease in speeds. What setting(s) could create such a situation where hardwired D/L and U/L speeds go from 900+ to essentially half of that?

 

[Ripshod]

Just wondering if I could have changed a setting within the firmware in the spirit of optimizing that could have caused such a dramatic and consistent decrease in speeds

First thing would be a factory reset. Then do a minimal setup (internet, wifi ssid and password, and router password) then test again). The move from stock firmware to Merlin's necessitates a reset.

 

[PureSpeed]

In all honesty it could be a multitude of settings that can affect speed. I would do a hard reset on it. But if you have another spare router hanging around you can do a process of elimination and see if you get full speeds from a different router. I have seen some Asus routers fail and cause the speed reduction.

1. Try an older firmware prior to the one installed

2. Put a different router in check speeds that way especially hardwired speed

3. Completely hard reset the device not a software reset a full hard reset.

4. If nothing helps I’m thinking a switch problem and a replacement from Asus is necessary

 

[doczenith1]

First thing I would do is check the Tools tab to confirm NAT acceleration is on.

 

[KevTech]

The move from stock firmware to Merlin's necessitates a reset.

I think it is the other way around (merlin to stock).

 

[HH22]

Thanks for the helpful input thus far. Prior to hard resetting, I began to work through the various settings tab-by-tab. When I got to Adaptive QoS, I switched it (Enable QoS) to off. I had somewhat recently established a bandwidth limit for my Guest network and, when doing so, it has enabled QoS. Now, I would have thought it should have only limited speeds on the 2.4GHz only Guest network but apparently it was impacting my hardwired speeds as well. As soon as I disabled QoS (and there wasn't any information in the upload and download section below, BTW), I experienced a significant increase in speeds (up to ~850/940). So, it appears that was the major culprit.

I have also noticed turning off AiProtection returns 10 or so Mbps but don't know if that tradeoff is worth it?

I'll keep working through the settings to see if anything else is holding back the download speeds as they should be closer to the historical range of low 900s.

 

[HH22]

First thing I would do is check the Tools tab to confirm NAT acceleration is on.

View attachment 55695

Thanks. They were indeed turned on.

 

[aex.perez]

Turning on anything that starts up the BWDPI Engine (TrendMicro) will do that, Qos, Parental Controls, Time Scheduling to name a few. See Bandwith Monitor/Data Classification. If you see any active stats, something enabled the BWDPI Engine.

Lots of history starting wih my 1Gb bandwith cutting in half, whe something enables the BWDPI Engine (TrendMicro), difference is that I now know what to look for to fix it...
Los here , I too had and have fixed the issue...

Case in point, the last time the BWDPI Engine got enabled from some setting, see the dip in Bandwidth

Some History (a.k.a my scars) to poke around through,

Skynet / dnsmasq / Flowcache / Merlin 388 releases

No one knows. As per this post there is something else used. This is not that important. What is important very often what I find issues with in 388 firmware works well in later 386 firmware. In my understanding and experience so far firmware version below 38x.4xxxx -> user as a beta tester.

www.snbforums.com

[ 3004.388.5 alpha Build(s) ] Testing available build(s)

LOL Not sure what makes it work for 24h already, but... that works 160Mhz and it actually counts!

www.snbforums.com

[ 3004.388.5 alpha Build(s) ] Testing available build(s)

LOL Not sure what makes it work for 24h already, but... that works 160Mhz and it actually counts!

www.snbforums.com

[ 3004.388.6 alpha Build(s) ] Testing available build(s)

No, the problem did not exist under 388.5. You could have posted this A LITTLE sooner... ;) I just downgraded to 388.5 and verified that the error wasn't there.

www.snbforums.com

Beta - Asuswrt-Merlin 3004.388.6 Beta is now available

I have two (2) remote sites that I manage that have RT-AX88U as primary router. I just verified QOS was NOT enabled on its own for either with the upgrade to 3004.388.6 beta1 (from 3004.388.6 alpha1). See if Bandwidth Monitor and/or data classification is working for you. I did find a few...

www.snbforums.com

 

[sfx2000]

FWIW - try rebooting the modem - I've seen this from time to time where my WAN side performance dropped significantly - and rebooting the router didn't change things, but rebooting the cable modem did (Moto/Arriss SB8200)