Solved RT-AC86U not able to authenticate or DHCPACK(br0) 2.4Ghz clients after 2-4 days (Merlin 384.8_2)

[Arrow]

- DoS protection was enabled
- unreplied UDP timeout is set to 15 to help avoid potential NAT corruption with SIP clients
- 2.4 Ghz running at 53C, CPU at 69C
- -49 dBm on 2.4 Ghz ... it's not a signal strength issue
- it's also highly unlikely that it's an interference issue ... read below, please
- wireless MAC filtering is enabled ... yes, I know it doesn't necessarily help with security
- all clients are assigned static IPs
- Smart Connect is disabled
- 2.4 Ghz SSID is not the same as the 5 Ghz SSID (channels are also manually assigned after using inSSIDer)
- Bluetooth Coexistence is set to pre-emptive
- Nothing is attached to USB 3.0
- This is the second RT-AC86U I've tried where 2.4 Ghz clients drop but not because of wireless signal strength

Most 2.4 Ghz clients were dropping (all clients were unreachable over LAN) and not able to authenticate on some clients with "wrong password" errors. System logs don't show the block message when clients attempt to reconnect. The 2.4Ghz signal is still strong and broadcasting while the problem is occurring.

One client is a Logitech Harmony Hub, used with a Harmony Elite remote control. Another client is an Ecobee 3 thermostat running firmware version 4.2.0.394, which is the latest firmware according to Ecobee. Other clients connecting to 2.4Ghz, which I doubt are important, include three Wyze Pan Cams and some iPhones. Oddly, the Ecobee 3 was still showing as being connected and so were two Wyze Pan Cams, but the Ecobee 3 and all Wyze Pan Cams were unreachable over the LAN and weren't able to connect to WAN. The other Wyze Pan Cam simply wasn't listed in the client list under "view list" in Network Map.

First, I disabled DoS protection. That didn't seem to change anything with respect to trying to reconnect other devices manually back to 2.4 Ghz.

After about 20 minutes of looking at settings and router logs, I unplugged the Harmony Hub. That didn't seem to didn't seem to change anything with respect to trying to reconnect other devices manually back to 2.4 Ghz. I plugged the Harmony Hub back in.

Then I removed the Ecobee 3 thermostat from the wall and reconnected it. At that point, all 2.4Ghz clients automatically reconnected, first starting with Harmony Hub, an iPhone, and then the Ecobee 3, which takes a little while to boot up. DoS protection was still disabled at this point.

At no point was the router rebooted or turned off. At no point did 2.4Ghz signal drop and return. No microwaves were in use.

I've contacted Ecobee. The response I received indicated they have no idea. It doesn't seem coincidental that almost as soon as I unplugged and reconnected the Ecobee 3, all 2.4 Ghz clients reconnected and worked. I did come across a reddit thread that suggested contacting Ecobee in order to disable power saving mode in the Wi-Fi chip, but all newer Ecobee firmwares don't have the power saving mode issue. That Reddit thread was for an Ecobee 4, and this issue involves an Ecobee 3.

Does anyone have an idea what might be going on? This problem doesn't seem like 2.4Ghz is dying in the router, and this is the second one I've tried where the problem occurs by the fourth day. What would be causing DHCPACK not to be issued to any 2.4 Ghz client due to something involving the Ecobee 3 after 2-4 days?

 

[RMerlin]

https://www.snbforums.com/threads/guide-troubleshooting-wifi-issues.12825/

 

[Arrow]

https://www.snbforums.com/threads/guide-troubleshooting-wifi-issues.12825/

Thank you for your response. The only thing I haven't done in that list is to delete previously saved Wi-Fi configurations on the clients. I'll do that now. I've not had this issue using Merlin firmware on older Asus routers. I understand that just because something worked on a different router doesn't mean it will work on a newer one.

I don't feel it's a signal strength or interference issue. Rather, it's something involving dhcp, but without system logs indicating a connection has been blocked or something else has been rejected, it's difficult to troubleshoot. If the issue involves the Ecobee and power saving mode, which shouldn't be enabled in the those thermostats using the latest firmware, then I guess I could try disabling WMM APSD to see if that helps.

The problem is something involving either an Ecobee 3 or a Logitech Harmony Hub not getting a DHCP ack after 2 to 4 days and blocking the rest of my 2.4 GHz clients from receiving dhcp acknowledgments as well.

 

[RMerlin]

Have you disabled Beamforming and Airtime Fairness? These resolves a large majority of connectivity issues with smart devices / IoT devices.

 

[Arrow]

Thanks. Airtime fairness was off. Explicit beamforming was off. Universal beamforming was on. I've now disabled it.

 

[username0475]

Thanks. Airtime fairness was off. Explicit beamforming was off. Universal beamforming was on. I've now disabled it.

Any improvements?

 

[Arrow]

Any improvements?

2.4Ghz has been working fine for over 114 hours, but I also disabled "Enable WMM APSD" because I had a sneaking suspicion it was causing problems with Ecobee 3 thermostat and because I have a limited return window for testing purposes. I am going to test with "Enable WMM APSD" enabled this weekend.

 

[Arrow]

Have you disabled Beamforming and Airtime Fairness? These resolves a large majority of connectivity issues with smart devices / IoT devices.

The issue appears to have been Beamforming.
After I disabled Universal beamforming, the problem went away.
2.4Ghz has been up for over 152 hours without dropping any clients.
Thank you very much

For people with an Ecobee 3 and, perhaps, a Logitech Harmony Hub, disabling these three settings works for me for 2.4 Ghz:
1) Airtime Fairness, (to be fair, I had Airtime Fairness off and was still encountering problems)
2)Explicit Beamforming, and
3)Universal beamforming.

 

[Arrow]

Well, I updated to Merlin 384.9 yesterday, and the problem returned today. I didn't do a factory reset after updating last night.

All clients either dropped 2.4Ghz or couldn't connect to the internet using it this afternoon.

I unplugged the Ecobee 3 from the wall and plugged it back in to see if all devices would reconnect again. They didn't.

I unplugged the Harmony Hub and plugged it back in. All 2.4 Ghz clients reconnected.

That's the complete opposite behavior from last time. I'm not positive whether both devices (Harmony Hub and Ecobee 3) are causing the problem or just one.

I'm not sure if I should save router settings, do a factory reset, and then restore router settings or if I should try disabling "Enable WMM APSD" again. I guess the easiest thing to try is disabling "Enable WMM APSD" again.

 

[Arrow]

Just got disconnected again. This time I just unplugged the Logitech Harmony Hub and plugged it back in. All 2.4 Ghz clients automatically reconnected.

I'm going to try a factory reset and restore router settings without WMM APSD being disabled.

 

[bbunge]

Also recommend you set 2.4 GHZ to fixed channel with 20 MHZ bandwidth and 5 GHZ to fixed channel.

Sent from my SM-T380 using Tapatalk

 

[Arrow]

https://www.snbforums.com/threads/r...-clients-after-2-4-days-merlin-384-8_2.54617/

- 2.4 Ghz SSID is not the same as the 5 Ghz SSID (channels are also manually assigned after using inSSIDer)

Also recommend you set 2.4 GHZ to fixed channel with 20 MHZ bandwidth and 5 GHZ to fixed channel.

The channels are manually assigned. This issue doesn't involve 5Ghz at all.
Yes, 2.4Ghz has been set to 20MHz this entire time.

I'm currently testing after doing a factory reset and restoring settings.

 

[Arrow]

My issue involves the Harmony Hub only. I'm not sure why it's happening though.

 

[Kingp1n]

My issue involves the Harmony Hub only. I'm not sure why it's happening though.

Did you end up fixing this ? I was having 2.4 dropouts and I'm getting a replacement rt-ac86u from Asus next week. Let's hope this will fix the issue

 

[elardner]

Having similar issues with 2.4GHz dropping. I am using smart connect (have also tried breaking up the frequencies), have disabled MU-MIMO, beamforming and Airtime Fairness to no avail. I can't find any settings that will convince the 2.4GHz devices to connect. This is my second router from Asus after the return of the first for the same issues.

Unplugged my Harmony Hub, hoping that would be the solution, didn't help.

My chromebook gives an error about DHCP issues when I try to force it to connect to the 2.4GHz network...

The TP-Link Switches that are trying to use the 2.4GHz network show this in the system log over and over again as they are trying to connect:

May 2 19:23:17 dnsmasq-dhcp[767]: DHCPOFFER(br0) 192.168.50.230 70:4f:57:ee:a9:a6
May 2 19:23:17 dnsmasq-dhcp[767]: DHCPDISCOVER(br0) 70:4f:57:f9:c9:22
May 2 19:23:17 dnsmasq-dhcp[767]: DHCPOFFER(br0) 192.168.50.92 70:4f:57:f9:c9:22
May 2 19:23:19 dnsmasq-dhcp[767]: DHCPDISCOVER(br0) b0:ee:45:49:6b:60
May 2 19:23:19 dnsmasq-dhcp[767]: DHCPOFFER(br0) 192.168.50.212 b0:ee:45:49:6b:60
May 2 19:23:19 dnsmasq-dhcp[767]: DHCPDISCOVER(br0) 70:4f:57:ee:a9:a6
May 2 19:23:19 dnsmasq-dhcp[767]: DHCPOFFER(br0) 192.168.50.230 70:4f:57:ee:a9:a6
May 2 19:23:19 dnsmasq-dhcp[767]: DHCPDISCOVER(br0) 70:4f:57:f9:c9:22
May 2 19:23:19 dnsmasq-dhcp[767]: DHCPOFFER(br0) 192.168.50.92 70:4f:57:f9:c9:22
May 2 19:23:21 dnsmasq-dhcp[767]: DHCPDISCOVER(br0) 70:4f:57:ee:a9:a6
May 2 19:23:21 dnsmasq-dhcp[767]: DHCPOFFER(br0) 192.168.50.230 70:4f:57:ee:a9:a6
May 2 19:23:21 dnsmasq-dhcp[767]: DHCPDISCOVER(br0) 70:4f:57:f9:c9:22
May 2 19:23:21 dnsmasq-dhcp[767]: DHCPOFFER(br0) 192.168.50.92 70:4f:57:f9:c9:22

 

[Arrow]

I'm not sure which Merlin firmware update fixed this problem, but the issue has no longer existed for quite some time.

 

[lala_cai]

Which firmware are you currently in now? I’m facing this issue with the newer firmwares which started from 384.18.

 

[Arrow]

Which firmware are you currently in now? I’m facing this issue with the newer firmwares which started from 384.18.

386.1.2

A. On 2.4 Ghz, I am using the least crowded control channel at my location. I'm using 11 and Below.

B. Channel bandwidth is 20/40, but if you're having problems, set this to 20.

C. Disable Smart Connect, and use separate network names for 2.4 and 5 Ghz bands.

D. On the Professional Tab for 2.4, make sure that Bluetooth Coexistence is enabled.

E. Disable Universal Beamforming

F. Disable Airtime Fairness

G. Keep router away from microwave ovens.



The problem had nothing to do with DoS Protection being enabled.

Ecobee thermostat and Harmony Hub were updated to latest firmwares. Contact support numbers if you require help updating.

 

[Smokey613]

I have had similar issues with some of my 2.4g devices for a long time. The one thing that solved it for me was making sure the 2.4g was using Modulation Scheme MCS 7 and not MCS 9 in the Professional settings. This also solved the same issues with two of my friends running Asus routers.

 

[gattaca]

^^^^ Good point. I have a really old laptop which would not connect to my AC86U ... and I'm betting that setting is on like 11... without even looking b/c I did not alter it.