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

[BosseSwede]

FOLLOW-UP
Now after having received the new ASUS RT-AX86U Pro router I am preparing to migrate to that router and as part of that I am noting down all the settings on the old RT-AC86U router.
While doing the list of DHCP reservations I also wanted to identify the WiFi of my Panasonic Heat-Pump which is running here. It was connected to WiFi when it was installed back in spring of 2024 and is accessed via a Panasonic App (Comfort Cloud) from my phone. That runs via a cloud service by Panasonic over Internet.
Since I want to have control over my LAN I wanted to put that device into the DHCP reservations list and to do that I needed to identify it on my LAN.
In the RT-AC86U router admin pages there is a client list where I could identify most of the connected clients leaving only a couple of unknowns. I suspected one in particular so I used a Linux machine to ping the shown IP address, which responded.
Then I switched off power to the heat-pump and its WiFi lamp went out. And now no response to ping.
So I thought the device was identified and switched on heat-pump power again.
Now back in the router admin page I intended to give the entry a device name, but to my surprise the device is no longer shown even though I can access the heat pump via the app and switch on/off the fan etc!
I have checked that it responds properly to ping on the same IP address used before so it is there but the router is no longer listing it! I have tried multiple times to refresh the router's client list to no avail...

So my question now is why has this happened and is there a way to tell the router to *really* refresh the client list and show the connected devices?

 

[bennor]

Now back in the router admin page I intended to give the entry a device name, but to my surprise the device is no longer shown even though I can access the heat pump via the app and switch on/off the fan etc!

No longer shown where in the router GUI? The Network Map? The Client List? The Wireless Log? Manual DHCP IP reservation MAC list? Some other GUI page?
The Network Map, if you search these Asus subforums, is well known for having issues displaying clients correctly. As a troubleshooting step, reboot the router and see if the client show up in the Network Map.
Edit to add: Sometimes the Network Map "fixes" itself after a period of time and correctly shows all the clients.
One can try to kill the network map process (killall networkmap) by issuing the following command via SSH to see if the network map process restarts with the correct list of clients:

killall networkmap
Or some indicate the following works when killall network map does not:
killall -9 networkmap

 

[BosseSwede]

No longer shown where in the router GUI? The Network Map? The Client List? The Wireless Log? Manual DHCP IP reservation MAC list? Some other GUI page?

Admin page first shown on login is the "Network Map".
Right in the center: View List (of clients)
Click either the computer in circle button or the View List and two different ways of viewing the clients are popping up. But both still are missing the Heat-Pump WiFi client even though it is pingable...

As a troubleshooting step, reboot the router and see if the client show up in the Network Map.

I do not want to do that because it will disrupt everything else here....
There is a lot of real time stuff being done 24/7 on the various Linux devices I have.

All seems to be working just only this display in the admin page is missing. I took a screenshot earlier so I know how it looks like anyway.

I don't want to go beyond this now, better to focus on getting all the config data out of the router so I can put it into the replacement router....

 

[bennor]

Admin page first shown on login is the "Network Map".

Are the missing Network Map clients shown correctly on the System Log > Wireless Log page?
PS: If you don't want to reboot then see the killall networkmap command (i mentioned in my prior post) fixes the issue. Or just wait it out and maybe the Network Map will fix itself.