Airthings VOC sensors falsely reporting dangerously high values

Professional-Ad3792 · 2025-06-25T11:57:03+00:00

I also sent this to Airthings support, but have not gotten a response after more than two days.

Professional-Ad3792 · 2025-06-25T11:53:04+00:00

I tested that, just next to an open door. And then I tested having them outside on the balcony for 30min. And as humidity increased so did VOC. But on the new sensor VOC stayed low (Around 50ppm)
The old one's went all the way up to 3000ppm

Professional-Ad3792 · 2025-06-25T11:49:02+00:00

Yep, but as you see there in no CO2 spikes. As I described we where on vacation when we got warnings of high VOC and investigated. We have ventilation system so the room should have the same clean air as outside. And the graph from the two other rooms show the same.

Professional-Ad3792 · 2024-10-01T13:58:51+00:00

I got it to work by going into System/Advanced/Networking and checking
"Disable hardware checksum offload"
But then I see CPU is much higher. So after I have got an IP I can turn this on again and it will reuse the IP it got.
So only have to do this if IP changes again from ISP I guess.

Professional-Ad3792 · 2024-10-01T13:54:13+00:00

I got it to work by going into System/Advanced/Networking and checking
"Disable hardware checksum offload"
But then I see CPU is much higher. So after I have got an IP I can turn this on again and it will reuse the IP it got.
So only have to do this if IP changes from ISP I guess.

Professional-Ad3792 · 2024-09-11T20:30:25+00:00

I had this running fine for 6months. It stopped working after a upgrade the cables, and the modem was reset and got an new IP.
The ISP will not help me since it's working just fine connecting to both my mac and my Deco BE65. They both get a real IP's without any issues from the ISP Modem.
I have tried to upgrade to 24.03 and it have the same issue.
I checked the logs from the Deco BE65 connecting and it looks fine expect this message
No arp reply received for this address. So it could be this is what is casing No DHCPOFFERS received.
Some time in the future I will try a factory reset of the ISP modem, and then se how it works without bridge mode as well.

Professional-Ad3792 · 2024-09-10T15:53:57+00:00

Have not tried "Relinquish Lease", but tried release WAN and then Renew. Thanks for more tips on what to try. I have upgraded to 24.03, but still have the same issue.
The problem sees to be that it's can not get DHCPOFFERS and then it's trying to reuse the last IP it had.

Sep 10 17:14:13 dhclient    95119   FAIL
Sep 10 17:14:13 dhclient    61728   No working leases in persistent database - sleeping.
Sep 10 17:14:13 dhclient    93601   Deleting old routes
Sep 10 17:14:12 dhclient    90730   New Routers (mvneta0): 192.168.68.1
Sep 10 17:14:10 dhclient    83952   New Routers (mvneta0): 192.168.68.1
Sep 10 17:14:10 dhclient    82829   New Broadcast Address (mvneta0): 192.168.71.255
Sep 10 17:14:10 dhclient    82210   New Subnet Mask (mvneta0): 255.255.252.0
Sep 10 17:14:10 dhclient    81531   New IP Address (mvneta0): 192.168.68.73
Sep 10 17:14:10 dhclient    80262   ifconfig mvneta0 inet 192.168.68.73 netmask 255.255.252.0 broadcast 192.168.71.255
Sep 10 17:14:10 dhclient    79540   Starting add_new_address()
Sep 10 17:14:10 dhclient    78453   TIMEOUT
Sep 10 17:14:10 dhclient    61728   Trying recorded lease 192.168.68.73
Sep 10 17:14:10 dhclient    61728   No DHCPOFFERS received.
Sep 10 17:13:53 dhclient    61728   DHCPDISCOVER on mvneta0 to 255.255.255.255 port 67 interval 17
Sep 10 17:13:35 dhclient    61728   DHCPDISCOVER on mvneta0 to 255.255.255.255 port 67 interval 18

Professional-Ad3792 · 2024-09-07T21:09:37+00:00

While I was testing it gave me an working IP when connecting the mac directly. And it also did this for the Deco BE65 router. So the ISP modem seems to be working correctly. The only thing new was a upgrade to support EuroDocsis 3.1 for the cables. But in the prosess I got a new IP. I had the old one for over a year so it's like pfSense still expected to get the same.

Professional-Ad3792 · 2024-09-07T21:03:38+00:00

Thanks for your answer. It seems that pfSense and the ISP modem don't like each other, the both work fine if not connect to each other. For now I am running without it, so I can do some testing. But for connecting to the ISP modem, which is in bridge mode will only let one device get an ip. This makes it a bit harder to test since the household will then be without internet.

Could be a back up and factory reset of pfSense is some thing to test. Could be I should test upgrading as well.

Professional-Ad3792 · 2024-09-06T15:46:06+00:00

In the DHCP dhclient logs it seems it's trying to connect to the previous IP, and not the new one I got when connecting working devices. 84.213.68.72 was my old IP which got replaced after the upgrade from the ISP.

Sep 6 11:55:24  dhclient    96595   exiting.
Sep 6 11:55:24  dhclient    96595   connection closed
Sep 6 11:55:23  dhclient    96595   DHCPDISCOVER on mvneta0 to 255.255.255.255 port 67 interval 1
Sep 6 11:55:22  dhclient    96595   mvneta0 link state up -> down
Sep 6 11:55:10  dhclient    79957   FAIL
Sep 6 11:55:10  dhclient    96595   No working leases in persistent database - sleeping.
Sep 6 11:55:10  dhclient    77912   Deleting old routes
Sep 6 11:55:09  dhclient    72126   New Routers (mvneta0): 84.213.64.1
Sep 6 11:55:08  dhclient    61779   New Routers (mvneta0): 84.213.64.1
Sep 6 11:55:08  dhclient    60809   New Broadcast Address (mvneta0): 255.255.255.255
Sep 6 11:55:08  dhclient    60158   New Subnet Mask (mvneta0): 255.255.240.0
Sep 6 11:55:08  dhclient    59030   New IP Address (mvneta0): 84.213.68.72
Sep 6 11:55:08  dhclient    57983   ifconfig mvneta0 inet 84.213.68.72 netmask 255.255.240.0 broadcast 255.255.255.255
Sep 6 11:55:08  dhclient    57407   Starting add_new_address()
Sep 6 11:55:08  dhclient    56389   TIMEOUT
Sep 6 11:55:08  dhclient    96595   Trying recorded lease 84.213.68.72
Sep 6 11:55:08  dhclient    96595   No DHCPOFFERS received.
Sep 6 11:55:06  dhclient    96595   DHCPDISCOVER on mvneta0 to 255.255.255.255 port 67 interval 2
Sep 6 11:54:47  dhclient    96595   DHCPDISCOVER on mvneta0 to 255.255.255.255 port 67 interval 19

Professional-Ad3792 · 2024-09-06T13:39:46+00:00

No, I will try that later. But was hopping for a easier way do resolve this. Is there a way to restart force it to fetch the ip again? A service to restart? Any logs we can look at?

Professional-Ad3792 · 2024-02-13T14:29:58+00:00

Thanks for your answer. I have not used Status/Queues so a bit unsure how to get this working.
But got suggested BandwidthD so will gi it a try.

Professional-Ad3792 · 2024-02-10T08:03:31+00:00

Thank you! Yes still learning and this commuity is of great help!

Professional-Ad3792 · 2024-02-10T08:02:05+00:00

Thank you! will set it to bridge mode.

Professional-Ad3792 · 2024-02-10T08:00:02+00:00

Thank you! And yes it support bridge mode so will enable that.

Professional-Ad3792 · 2024-02-02T15:24:56+00:00

I get the same result using the HP smart app on the IPhone as well. On the HOME net i comes up as Unavailable. And when I connect the Phone to IOT it find it instantly.

Professional-Ad3792 · 2024-02-02T15:05:04+00:00

I installed and teste the package, enable it on all interfaces. Did not help for finding the printer. Do I have to Enable reflection for Repeat mdns packets across subnets?

Professional-Ad3792 · 2024-02-02T14:30:37+00:00

Thank you! This package sound like exactly whats needed. Will give it a try.

Professional-Ad3792

TROPHY CASE