RT-AC86U refusing to connect some devices - router reboot fixes problem - why?

[BosseSwede]

I have an RT-AC86U router at my summer home with a 250 MBPS fiber connection to the Internet.
The network has some devices hooked up by Ethernet cable but there are also a number of WiFi devices like TV:s, Cellphones, RaspberryPi:s and my Panasonic heat pump.
In total there are 10 WiFi and 9 Ethernet connected devices (according to the client list on the router).

CURRENT PROBLEM
About a month ago I had a connection issue with an ESP8266 based electricity meter reader which is reporting the meter data via MQTT to my server.
It did not connect to the WiFi even when I power cycled it while at the same time everything else worked fine.
After a lot of attempts I discussed it with my son-in-law who suggested that I reboot the router. To me that did not make much sense since all other WiFi connected devices worked just fine, but a s last resort I did the reboot.
And then the ESP8266 reader connected normally!!!

Fast forward to yesterday when I suddenly could not reach the Panasonic heat pump from the app on my phone and the WiFi lamp on the indoor fan was blinking.
Again my other normally used WiFi devices like phones etc worked just fine, until I checked the electricity meter reader and it was also off line!

So now I had 2 devices that could not connect WiFi...

This time I rebooted the router yet again and lo-and-behold, both problem devices were able to connect and resume operations!

QUESTION 1:
Why is this happening and is there some router setting I can modify somewhere to make it NOT behave like this?
The router is running the latest f/w 3.0.0.4.386_51967

I am currently living at the summer home but in a month I will move back home 100 km away and servicing becomes so much more difficult.

QUESTION 2:
How can I find the MAC address of the Panasonic heat pump?
The router's list of connected devices is fairly long and I don't know how to identify the Panasonic device.
I want to secure a DHCP reservation for it so I can try and contact it when there are problems but without the current IP address or the MAC address I don't know how that can be done.

 

[degrub]

For max compatibility and fewer issues
set separate SSIDs for 5 and 2.4 GHz bands, no special characters in pswd
set channel width to 20 MHz, channel id to fixed - 1,6, or 11 maybe.
Use WPA2 personal. Some devices need TKIP instead of AES
Turn off any roaming assist, smart connect

Typically MAC addresses are on a label on the device. You may have to read the manual for setup or it may use WPS.

 

[bbunge]

The AC86U is known for having sudden hardware failures. Best to invest in a new router.

Using Dual Band Smart Connect is OK in spite of what some old school folks say....

The MAC address should be on the heat pump nameplate.

 

[OzarkEdge]

Using Dual Band Smart Connect is OK in spite of what some old school folks say....

I use it... but some clients do not tolerate it.

For instance, I setup an AX86U using SC... the 2.4/5.0 LG TV 20' away refused to stay connected to 5.0.... kept dropping to 2.4 and stuttering. So I disabled SC and used different SSIDs.

A year later, I updated that AX86U, tested SC, and the TV now has no issues sticking to 5.0. The only thing that changed was the firmware on both ends. Great, now using SC on Main, and Guest2 (internet access only), all with WPA2/WPA3.

Then I tried to setup a new 2.4 water heater... its app refused to find the Guest2 2.4 WLAN. So, I temporarily disabled the Guest2 5.0 WLAN, setup the heater, and then re-enabled the Guest2 5.0 WLAN. The heater itself tolerates using SC.

Last trouble (WPA2/WPA3 issue) was a new 2.4 clock/radio client with an app that refused to setup. I figured it did not like WPA2/WPA3 on the Guest2 WLAN, so I added a Guest3 2.4 only WLAN with WPA2 only and that allowed the setup to finish. Later I also had to allow intranet access so the owner could use the app on Main to access the clock on Guest3... not IoT secure, but what they wanted.

Pretty much anything can have issues that may matter to the owner. My goal was to use SC, WPA2/WPA3, and isolate as many clients as possible on Guest2 with no intranet access. The clock/radio client fell short but now the owner has an IoT WLAN of last resort to connect difficult IoT clients... and will be more ready for the next update to VLANs.

OE

 

[bbunge]

I use it... but some clients do not tolerate it.

For instance, I setup an AX86U using SC... the 2.4/5.0 LG TV 20' away refused to stay connected to 5.0.... kept dropping to 2.4 and stuttering. So I disabled SC and used different SSIDs.

A year later, I updated that AX86U, tested SC, and the TV now has no issues sticking to 5.0. The only thing that changed was the firmware on both ends. Great, now using SC on Main, and Guest2 (internet access only), all with WPA2/WPA3.

Then I tried to setup a new 2.4 water heater... its app refused to find the Guest2 2.4 WLAN. So, I temporarily disabled the Guest2 5.0 WLAN, setup the heater, and then re-enabled the Guest2 5.0 WLAN. The heater itself tolerates using SC.

Last trouble (WPA2/WPA3 issue) was a new 2.4 clock/radio client with an app that refused to setup. I figured it did not like WPA2/WPA3 on the Guest2 WLAN, so I added a Guest3 2.4 only WLAN with WPA2 only and that allowed the setup to finish. Later I also had to allow intranet access so the owner could use the app on Main to access the clock on Guest3... not IoT secure, but what they wanted.

Pretty much anything can have issues that may matter to the owner. My goal was to use SC, WPA2/WPA3, and isolate as many clients as possible on Guest2 with no intranet access. The clock/radio client fell short but now the owner has an IoT WLAN of last resort to connect difficult IoT clients... and will be more ready for the next update to VLANs.

OE

Right, a guest WIFI is the way to go for IOT clients. Setting the 2.4 GHz to 20 MHz on a fixed channel is best. The guest WIFI can be set to use WPA/WPA2-Personal which is better for older clients.

Still I would bet the OP's AC86U is failing. I am about to replace my old AC86U that I gave to a deserving family with an AX86U.

 

[OzarkEdge]

Still I would bet the OP's AC86U is failing.

Me, too.

OE

 

[BosseSwede]

Still I would bet the OP's AC86U is failing. I am about to replace my old AC86U that I gave to a deserving family with an AX86U.

I have replaced my router at home (also an AT-RC86U) with an RT-AX86U PRO about 5 months ago, but it was a hazzle to set it up like the old one so I would rather not do that again. Unless one can transplant the settings from one to the other, is that possible?
Of course my home router has a lot more to do since it is serving my OpenVPN server as well as a webserver and a Subversion server so there are a lot of routing and port forwarding going on on that system.
Not so much on my summer home router. It is just connecting my network over here back to my home LAN using the OpenVPN server there.

 

[CaptainSTX]

For max compatibility and fewer issues
set separate SSIDs for 5 and 2.4 GHz bands, no special characters in pswd
set channel width to 20 MHz, channel id to fixed - 1,6, or 11 maybe.
Use WPA2 personal. Some devices need TKIP instead of AES
Turn off any roaming assist, smart connect

Typically MAC addresses are on a label on the device. You may have to read the manual for setup or it may use WPS.

If the firmware on the AC86 allows you to select AES-TKIP then run a WiFi analyzer on some device to be sure the router is actually offering this method of encryption. Based on my testing neither Beta 4 or Beta 5 provide TKIP even though it is possible to select and apply AES-TKIP on Beta 5.