IOT device loses connection after a while because of unsuccessful DHCP

[bnl]

I have an Air Purifier which is wirelessly connected to my network. It loses internet connection after 1 to 3 days. After it loses its internet connection I unplug and plug the power cord. After I do this it connects within a few minutes. I can also disconnect the client in my WAP controller and when I do this it also reconnects within a few minutes.

I have the following network configuration:
OPNsense router
a few managed layer 2 switches
a few WAPs

The Air Purifier has excellent wifi signal as checked in my WAP controller, it is within 3 meters of a WAP which is mounted on the ceiling and has line of sight. It always connects to this closest WAP. This WAP is connected as follows: WAP-switch-switch-OPNsense

When the device loses internet connection, it still stays connected to the Wifi as I can see in WAP manager. Even after a few days it's still connected.
It seems to be a DHCP issue.
If I look in the Dnsmasq log I see a continuous DHCPOFFER - DHCPDISCOVER loop.
When I unlug the unit and power it again, I see about 10 times DHCPOFFER - DHCPDISCOVER, before I see it followed by DHCPREQUEST, DHCPACK. When it loses connection after 1-3 days, sometimes 10 hours, sometimes 2,5 days (it's random). It fails and keeps looping, I see thousands of entries in the log for a day.
Weirly, the time after which it loses connection looks random to me and is not related to the lease time. I can set a lease time of a day or an hour or a minute in dnsmasq for this device. Makes no difference on when it loses internet connection.

I tried a lot of different things but none of them fixed the issue and I don't know where to look next.
Maybe it's not me, but the device that has poor code? It's a high end device so you'd think it can't be that everyone is having this issue.
All my other devices (IOTs, laptop, phones, watches) work perfectly. Although I do see some DHCPREPLY-DHCPCONFIRM loops when I look at my iphone in the log.

Things I tried:
- I recently changed my DHCP server from ISC-DHCP to Dnsmasq. I had to change anyway at some time so I thought might as well check if there's an issue with ISC-DHCP. Didn't solve the issue.
- I changed the lease time
- I tried giving it a static ip address
- I tried using a different SSID on my WAP to which I only assigned 2.4Ghz and not also 5Ghz.
- I tried using WPA2 instead of WPA3
- I tried disabling spanning tree protocol on my switches

Any advice on what it could be and what I could try next?

[newsense]

Probably a faulty wifi implementation in the air purifier side. Check with the vendor if there are any firmware updates or known workarounds

[nero355]

Maybe it's not me, but the device that has poor code?

Probably that or maybe you have hit some kind of weird compatibility issue between the Air Purifier and your Accesspoint ??

I would e-mail both companies involved and ask them for a solution! :)

It's a high end device so you'd think it can't be that everyone is having this issue.

These days we all get to buy products that are basically put on the market in their Beta/Testing stage and then most of them get a lot of fixes for many months/years after their release, so don't count on that ;)


But may I ask which products you are talking about exactly and what the software and firmware versions are for both ?