What's going on with my RT-AC86U?

[TheConsultant]

Hi, this forum has been a goldmine of information but I've been unable to find anything that pertains to the combination of symptoms I'm experiencing.

I'm in the UK, running a stock AC86U as a single AP (no AiMesh in use), latest firmware (has always been kept up to date) - and in the past few days, I've noticed the 5GHz performance has fallen off a cliff. This is across multiple devices - naturally most noticeable on Android and iPhones which are used around the house the most. Used to be able to get a medium 5GHz signal in our living room, now the signal is non-existent. I know that 5GHz doesn't have great range, but it was usable before, and now it's as if someone put a sheet of lead in the internal wall overnight. Using WiFi analyser app on my phone shows that my 5GHz network strengths in the living room are comparable with the extremely faint signals from neighbouring houses, even though they are really far away compared to my router (at a minimum, 4-5x the distance).

In addition, it seems that signal strength fluctuates massively - it can be great, then suddenly drops. Sometimes the device will then disconnect and take ages or multiple attempts to reconnect. I've also noticed this stalling, dropping and reconnecting is happening on 2.4GHz as well, which I'm guessing corresponds to the multiple log entries such as "wlceventd_proc_event(511): eth6: Disassoc XX:XX:XX:XX:XX:XX, status: 0, reason: Disassociated because sending station is leaving (or has left) BSS (8), rssi:0" (However, 2.4GHz reach and performance seems fine and stable in all other regards, and the wired connections are fine too).

Even when sat right next to the router like I am now, my Android phone shows full WiFi signal strength on 5GHz, but in the client list on the router it's showing at the minimum.

I saw in the internal logs yesterday an event about CPU1 shutting down for thermal management which would be consistent with the problems I've read about here - I'm now capturing the logs in my Synology NAS but it hasn't yet re-occurred. CPU usage on both cores is typically 1-5%, and RAM usage around 80%.

It feels as though one of the 5GHz radios is on the blink given the drop-off in performance and bandwidth, but am not sure how to check or what else I can do to diagnose. Any advice appreciated!

 

[OzarkEdge]

Hi, this forum has been a goldmine of information but I've been unable to find anything that pertains to the combination of symptoms I'm experiencing.

I'm in the UK, running a stock AC86U as a single AP (no AiMesh in use), latest firmware (has always been kept up to date) - and in the past few days, I've noticed the 5GHz performance has fallen off a cliff. This is across multiple devices - naturally most noticeable on Android and iPhones which are used around the house the most. Used to be able to get a medium 5GHz signal in our living room, now the signal is non-existent. I know that 5GHz doesn't have great range, but it was usable before, and now it's as if someone put a sheet of lead in the internal wall overnight. Using WiFi analyser app on my phone shows that my 5GHz network strengths in the living room are comparable with the extremely faint signals from neighbouring houses, even though they are really far away compared to my router (at a minimum, 4-5x the distance).

In addition, it seems that signal strength fluctuates massively - it can be great, then suddenly drops. Sometimes the device will then disconnect and take ages or multiple attempts to reconnect. I've also noticed this stalling, dropping and reconnecting is happening on 2.4GHz as well, which I'm guessing corresponds to the multiple log entries such as "wlceventd_proc_event(511): eth6: Disassoc XX:XX:XX:XX:XX:XX, status: 0, reason: Disassociated because sending station is leaving (or has left) BSS (8), rssi:0" (However, 2.4GHz reach and performance seems fine and stable in all other regards, and the wired connections are fine too).

Even when sat right next to the router like I am now, my Android phone shows full WiFi signal strength on 5GHz, but in the client list on the router it's showing at the minimum.

I saw in the internal logs yesterday an event about CPU1 shutting down for thermal management which would be consistent with the problems I've read about here - I'm now capturing the logs in my Synology NAS but it hasn't yet re-occurred. CPU usage on both cores is typically 1-5%, and RAM usage around 80%.

It feels as though one of the 5GHz radios is on the blink given the drop-off in performance and bandwidth, but am not sure how to check or what else I can do to diagnose. Any advice appreciated!

Sounds like failing router hardware. As a last ditch effort, disconnect all LAN and USB except your admin PC, hard reset the firmware, configure minimally from scratch and then check for normal WiFi operation again. To be a bit more thorough, you could first reflash the firmware from a fresh download.

If you login to the webUI and browse to subpage /ajax_coretmp.asp, you can see if CPU temp is <86C (85% Tj max).

OE

 

[Smokey613]

I noticed the high temp condition reported. You might try using a small fan directed at the back of the router to see if it helps to reduce operating temps.

 

[TheConsultant]

If you login to the webUI and browse to subpage /ajax_coretmp.asp, you can see if CPU temp is <86C (85% Tj max).

Many thanks, that's handy to know! This is what it shows:

fanctrl_info = ; curr_cpuTemp = "98.875"; curr_rxData = fanctrl_info[3]; curr_coreTmp_2 = fanctrl_info[1]; curr_coreTmp_5 = fanctrl_info[2];

 

[Piotrek]

98.875

CPU temperature is too high.

 

[TheConsultant]

CPU temperature is too high.

Indeed, I wasn't wanting to see it that high. I guess that after 5 years, it's on it's way out. Shame as it's been a great unit.

I don't have a backup router I can drop into place, nor do I want to rely on rigging up fans for something I'm dependent on for work and so much more (we have Sonos speakers, smart lights, NAS storage etc) - so guess I'd better start looking at a replacement.

Anyone have any thoughts on what the recommended successor is to the RT-AC86U? Is it a no-brainer to look at the AX86U as a replacement, or are there any known issues with that, such as the thermal issues of the AC86U?

And since when did routers get so expensive? This one cost me well under £100 at the end of 2018, now they seem to be £200+!

 

[OzarkEdge]

Many thanks, that's handy to know! This is what it shows:

fanctrl_info = ; curr_cpuTemp = "98.875"; curr_rxData = fanctrl_info[3]; curr_coreTmp_2 = fanctrl_info[1]; curr_coreTmp_5 = fanctrl_info[2];

That's too hot. If you are not up to redoing the CPU thermal interface to its heatsink, and a case fan doesn't help; then you may want to replace the WiFi5 router with known hardware issues with a WiFi6 router... consider the RT-AX86U Pro/U/S... the Pro version will be getting 'next gen' firmware (3.0.0.6.*?) with hopefully better Guest Networking, etc.

I bought a AX86U Pro (curr_cpuTemp = "75.749") recently on sale for $234 from Newegg.com... the pandemic has bumped up prices and depressed availability, but this is easing a bit.

(I'm not too pleased with Newegg's new ownership but they are offering good sale prices from time to time... if you live in the US, give them your full ZIP+4 code for accurate sales tax).

I had two 2018 China AC86Us fail due to a voltage regulation chip burning out... I would not redo the CPU heatsink unless you really want to play with it.

OE

 

[FernandoF]

Anyone have any thoughts on what the recommended successor is to the RT-AC86U? Is it a no-brainer to look at the AX86U as a replacement, or are there any known issues with that, such as the thermal issues of the AC86U?

I bought a AX86U Pro (curr_cpuTemp = "75.749") recently on sale for $234 from Newegg.com... the pandemic has bumped up prices and depressed availability, but this is easing a bit.

To expand on the above question from @TheConsultant, I'm also starting to look at candidates to replace my RT-AC86U in the future. Even though I'm not based in the US, I was there recently and it seems the RT-AX86U Pro, GT-AX6000, and RT-AX88U Pro all share similar hardware and can be currently purchased for approximately the same price.

To me, range and internal temperatures would be among the key deciding factors. I've read all sorts of reports regarding range (unsurprisingly), so maybe there's not a clear winner. As far as temperatures, initial reports seem to indicate the GT-AX6000 and RT-AX88U Pro may run a little cooler (60-65°C) than the RT-AX86U Pro (75°C per @OzarkEdge). But I guess we need more data points.

Like the OP, I would also be interested in hearing perspectives on those 3 models as potential replacements to the AC86U. Thanks in advance.

 

[Smokey613]

Mine has never been higher than 69 degrees on my RT-AX86U Pro.

 

[OzarkEdge]

I'm currently at 74C... I'll keep an eye on it but I'm not concerned as long as it runs under ~86C. I'm using all LAN ports, the 2.5G port, and trying 160MHz bw again (which has not dropped since I turned it on this morning)... I have no idea if any of this affects CPU temp... may just be variation in the CPU heatsink assembly.

OE

 

[OzarkEdge]

To expand on the above question from @TheConsultant, I'm also starting to look at candidates to replace my RT-AC86U in the future. Even though I'm not based in the US, I was there recently and it seems the RT-AX86U Pro, GT-AX6000, and RT-AX88U Pro all share similar hardware and can be currently purchased for approximately the same price.

To me, range and internal temperatures would be among the key deciding factors. I've read all sorts of reports regarding range (unsurprisingly), so maybe there's not a clear winner. As far as temperatures, initial reports seem to indicate the GT-AX6000 and RT-AX88U Pro may run a little cooler (60-65°C) than the RT-AX86U Pro (75°C per @OzarkEdge). But I guess we need more data points.

Like the OP, I would also be interested in hearing perspectives on those 3 models as potential replacements to the AC86U. Thanks in advance.

I suspect any of those models will serve well... pick the one that best suits your needs. I read somewhere here that the AX6000 will also be getting Pro firmware(?)... if you can tolerate its looks. I'm not a fan of 8 LAN ports... too many to disconnect/reconnect when required.

I've only used the AX86U and AX86U Pro... maybe the Pro has more/top range. ASUS claims (like they did for the AC86U):

• Expanded coverage – The exclusive ASUS RangeBoost Plus improves signal range and overall coverage

Having used the AC86U, AX86U, and now the AX86U Pro... I'd say the Pro range is at the summit like the AC86U was/is... no complaints.

If you sort through the above, you can see why I upgraded to the AX86U Pro (now with both nodes running AX, I'm trying 160MHz again in case the issue was not actually RADAR detected... we'll see).

Buy local so the WiFi conforms to your local regulations.

OE

 

[FernandoF]

Thanks a lot for the detailed response, @OzarkEdge. At the moment, none of those models are offered in my country - only the standard AX88U is. Let's see what happens in the coming months.

I'm using all LAN ports, the 2.5G port, and trying 160MHz bw again (which has not dropped since I turned it on this morning)... I have no idea if any of this affects CPU temp...

Based on my observations, both the LAN ports and the radio bandwidth affect the CPU temp:

• You could potentially mitigate the temperature increase due to the LAN port usage by enabling Energy Efficient Ethernet (EEE), if you were using Merlin firmware. With the AC86U, there is a 2°C CPU temperature drop when EEE is enabled. On the other hand, some people say doing so "might slightly increase latency" (whatever that means).
• When I moved up from 40MHz to 80MHz bandwidth, the 5GHz radio temperature did increase 4-5°C, but unfortunately I don't remember the exact impact to the CPU temperature.

 

[TheConsultant]

Today I've turned off the 5GHz radio completely, and CPU temp has dropped to about 81 degrees. Hopefully it will soldier on until I can find a decent deal on a replacement, because in the UK, the RT-AX86U is the same price as the RT-AX86U Pro, which is around £265.

The RT-AX88U Pro is even more, about £315. Crazy money for a router.

Once I have a replacement, I'm certainly tempted to have a go at repairing the heatsink (if that's what it is, rather than a failing chip or radio) and then be able to use it in an AiMesh setup, but don't want to have a DIY-repaired box as my primary (and only) router.

Thanks for all the comments and experiences with successor models, I'd be happy with either 86 or 88 Pro, but will monitor prices for a bit first.

 

[Tech9]

repairing the heatsink

Your router has leaked thermal transfer pad. The pads used are not the greatest quality and leak silicone compound over time. This is reducing the thermal transfer capabilities. Replacing the pad will drop CPU temperatures about 20C, but this router has multiple other common hardware issues and the repair is not worth it. You'll spend the time to fix the CPU temperature and some time later something else may go bad. Better get a new router.

 

[TheConsultant]

Your router has leaked thermal transfer pad. The pads used are not the greatest quality and leak silicone compound over time. This is reducing the thermal transfer capabilities. Replacing the pad will drop CPU temperatures about 20C, but this router has multiple other common hardware issues and the repair is not worth it. You'll spend the time to fix the CPU temperature and some time later something else may go bad. Better get a new router.

Oh I'll definitely need a new router, I can't rely on this one. Just that once it's replaced, I'm more inclined to open it up and tinker on with it with a view to having it available as a backup or as an AiMesh node.

I just haven't gone ahead yet as I'm grumpy at the price of replacements which is just nuts. No way can something that cost £80 at the start of 2019 now be worth £262 less than five years later - ridiculous price gouging by Asus and/or retailers.

 

[Tech9]

No way can something that cost £80 at the start of 2019 now be worth £262

What is this thing?

 

[TheConsultant]

What is this thing?

Asus 8x-series routers.

 

[Tech9]

You had RT-AX86U/S at £80 new at some point? I don't think so...

 

[TheConsultant]

You had RT-AX86U/S at £80 new at some point? I don't think so...

No, I don't think the AX line existed in 2018/2019? My AC86U was £80 - it's modern-day equivalent, the AX86U, is retailing for over three times that amount.

 

[doczenith1]

I saw in the internal logs yesterday an event about CPU1 shutting down for thermal management which would be consistent with the problems I've read about here - I'm now capturing the logs in my Synology NAS but it hasn't yet re-occurred. CPU usage on both cores is typically 1-5%, and RAM usage around 80%.

This happened to my 86U about a year ago. I placed a $16 AC Infinity MULTIFAN S4, Quiet 140mm USB Fan behind my router and it's been working fine ever since.