Hello, I'm trying to follow the [OAK4 Getting Started Guide](https://docs.luxonis.com/hardware/platform/deploy/oak4-deployment-guide/oak4-getting-started/) to simply connect my OAK 4 S device in any way to start working with it, but I'm not having any luck. I have connected it to a PoE+ switch on our LAN that should deliver 30W. When connecting the device to the switch, I can see the blue light being active with no red light prior to the blue light lighting up, indicating that there is no power issue at play. [upl-image-preview uuid=ed91feb5-36f7-48a5-91ea-277f9877553b url=https://discuss.luxonis.com/assets/files/2026-06-17/1781712092-997020-image.png alt={TEXT?}] The device is discovered in OAK Viewer, but when trying to connect to it, I get the following error message: > Device Check Failed > > Failed to check device OS version. Please try again. And then, nothing happens. [upl-image-preview uuid=7df46ab3-eaf7-41b7-87a3-d240abdf3ab7 url=https://discuss.luxonis.com/assets/files/2026-06-17/1781712257-59225-image.png alt={TEXT?}] Furthermore, the device is not visible using `oakctl list`. The same issue is present even if I connect it directly to my laptop using a PoE+ injector. **P.S** I have also tried connecting it directly to my laptop using a USB 3.1 cable. When doing so, it does not show up in OAK Viewer, but it does show up in `oakctl list` with the following information: ``` oakctl list +---+---------------+-----------+------------+-----+---------------+-------+ | # | Serial Number | Device | Connection | OS | Agent Version | Setup | +==========================================================================+ | 1 | 1953488627 | OAK4-S R9 | usb:0-20 | N/A | N/A | N/A | +---+---------------+-----------+------------+-----+---------------+-------+ ``` However, trying to do anything with it still doesn't work here. Running `oakctl device update` simply yields: ``` ⠙ Connecting ... oakctl command failed: 0: Incoming stream encountered an IO error (TLS connect): tls handshake eof 1: tls handshake eof ``` I would much appreciate any help I can get. Best regards, Oscar

[OAK 4 S] "Device check failed" in OAK Viewer

OscarBark

Hello,

I'm trying to follow the OAK4 Getting Started Guide to simply connect my OAK 4 S device in any way to start working with it, but I'm not having any luck.

I have connected it to a PoE+ switch on our LAN that should deliver 30W. When connecting the device to the switch, I can see the blue light being active with no red light prior to the blue light lighting up, indicating that there is no power issue at play.

The device is discovered in OAK Viewer, but when trying to connect to it, I get the following error message:

Device Check Failed

Failed to check device OS version. Please try again.

And then, nothing happens.

Furthermore, the device is not visible using oakctl list.

The same issue is present even if I connect it directly to my laptop using a PoE+ injector.

P.S

I have also tried connecting it directly to my laptop using a USB 3.1 cable. When doing so, it does not show up in OAK Viewer, but it does show up in oakctl list with the following information:

oakctl list
+---+---------------+-----------+------------+-----+---------------+-------+
| # | Serial Number | Device    | Connection | OS  | Agent Version | Setup |
+==========================================================================+
| 1 | 1953488627    | OAK4-S R9 | usb:0-20   | N/A | N/A           | N/A   |
+---+---------------+-----------+------------+-----+---------------+-------+

However, trying to do anything with it still doesn't work here. Running oakctl device update simply yields:

⠙ Connecting ...                                                                                                     oakctl command failed:
   0: Incoming stream encountered an IO error (TLS connect): tls handshake eof
   1: tls handshake eof

I would much appreciate any help I can get.

Best regards,

Oscar

Oskar-Luxonis

Hi @OscarBark - this may be two separate issues.

For the PoE/LAN connection, please first check that your host computer and the OAK4 are on the same subnet, and that firewall/VPN settings are not blocking discovery. If you know the camera IP, you can also try:

oakctl connect <device-ip>

Please also update oakctl on your host:

oakctl self-update

Then try again:

oakctl list
oakctl device update

For the USB case, the device showing OS: N/A / Agent Version: N/A together with tls handshake eof suggests that oakctl can see the device at the USB/ADB discovery level, but cannot talk to the device-side oak-agent service. This can happen with an outdated or unhealthy Luxonis OS / agent state.

If oakctl device update still fails, please connect using SSH/ADB and check the installed OS version:

cat /etc/os-release

Then choose the appropriate fallback update path from the Luxonis OS guide:
Luxonis OS update / flash guide

Since the device is visible over USB, the ADB/recovery update path is likely the next best option before doing a full OS flash. Full OS flash should be treated as the last step because it wipes user data.

Also see:
OAK4 Getting Started troubleshooting

OscarBark

Hello,

I have asserted that my laptop is on the same subnet as my camera (laptop IP = 192.168.1.167 and camera IP = 192.168.1.138).

Running oakctl connect yields the following:

> oakctl connect 192.168.1.138
✖ Failed to make connection.                                                                                                                                       oakctl command failed:
   0: Failed to make connection
   1: Incoming stream encountered an IO error (TCP connect): No connection could be made because the target machine actively refused it. (os error 10061)
   2: No connection could be made because the target machine actively refused it. (os error 10061)

Any attempts to run oakctl device update yields the error from the original post (tls handshake eof).

Furthermore, attempting to ssh into the device yields:
ssh_dispatch_run_fatal: Connection to 192.168.1.138 port 22: Connection timed out

(Note: I was able to read the fingerprint of the host though, and add it known hosts before the error above).

Since this is a fresh camera, I guess I will do a full OS flash.

EDIT: I was able to connect to the device using ADB, and get the OS information that way:

ID=luxonisos-rvc4
NAME="Luxonis OS RVC4"
VERSION="1.23.1"
VERSION_ID=r851-1.23.1
PRETTY_NAME="Luxonis OS RVC4 1.23.1"
IMAGE_REV="112c73e63a9576c7023b6692e249359b1439ae32"
MANIFEST_REV_REV="8ad1fdc"
BUILD_ID="20260107220615"

EDIT 2: In the end, I was able to resolve the issue by connecting to the device using ADB (oakctl adb shell) and performing the factory-reset command of agentconfd.

Oskar-Luxonis

OscarBark - thanks for the update and sorry for late reply. That confirms the device-side services/setup state were not healthy.

Your device was on Luxonis OS 1.23.1, so I would still recommend updating to the latest Luxonis OS after the reset. The update/recovery options are here:
Luxonis OS update / flash guide

Best,
Oskar