LN882H device suddenly stopped connecting to local network

[bausensi]

Describe the bug
This RGBCCT lightbulb I flashed OpenBeken to, worked wonderfully for weeks once adjusted for power save and current limits. I controlled it through Home Assistant connected to my local WiFi network with a static IP. The device worked flawlessly for several weeks, but one day it suddenly stopped responding to commands. Safe mode works well and AP mode accepts clients without any issues. But it cannot connect to the local network once configured, whether through DHCP or with a static IP, I tried both. Erasing the flash and changing the MAC address didn't fix the issue. I've tried several other APs including my mobile hotspot and it couldn't join a single one.

I did a teardown surgery on it and reflashed it but it didn't work. Once reset it became apparent only the AP mode worked. Upon attaching UART wires I found out it tries to connect to my local network and even though it seems to succeed, an error code is returned and tries again forever. I found no information anywhere about this error code and I'm not familiar with the source code to figure out a solution, so I request help here.

Firmware:

• Version: 1.18.177
• Device: Generic Tuya lightbulb based on W509Z2 kit
• Chip/model: LN882HKI
• Device config: RGBCCT based on BP5758

To Reproduce
Steps to reproduce the behavior:

1. Establish UART connection on RX1/TX1 pair at 921600 baud
2. Reset device in safe mode
3. Fill out SSID and password, set a static IP configuration
4. Enable WiFi network mode and restart device
5. See UART logs

Screenshots

Additional context
This is my only IoT device and it used to work well for 2 weeks.

[MaxineMuster]

I never heard about this and I fear, it will be hard to fix, at least only with the error code 0xc4.
This is because all WiFi related code is in a library provided as a binary blob by the vendor and I don't think even this code is documented...
Do you have the possibility to test another access point, maybe a "simple" one with only WPA2 in case your has WPA3?

[MaxineMuster]

Made a quick search in SDK for this code and only found one "near" match in bl (Bluetooth) code:

components/ble/mac/ble/hl/api/rwble_hl_error.h

/// Reserved slot violation
--
LL_ERR_RESERVED_SLOT_VIOLATION     = 0xC4,

[bausensi]

I never heard about this and I fear, it will be hard to fix, at least only with the error code 0xc4. This is because all WiFi related code is in a library provided as a binary blob by the vendor and I don't think even this code is documented...

Was afraid it'd be the case. It happened after updating to a newer 1.18 version. I recall one of these updated the LN882H WiFi blob, maybe downgrading to an older version will make the issue go away? I will try.

Do you have the possibility to test another access point, maybe a "simple" one with only WPA2 in case your has WPA3?

I was using WPA2/WPA3 for security, I will try my mobile hotspot with WPA2 only and report back

[bausensi]

Testing with other APs and security modes makes no difference. With my mobile AP on WPA2 only it continuously returns auth status 2 and tries to reconnect constantly, but I've triple checked SSID and passphrase matched. My local network AP is WPA2 and it used to work well with the LN882H until it stopped connecting. I believe the LN882H blob might be the culprit.

1.18.177 contains blob 1.5.0

[bausensi]

Okay, I've tried downgrading all the way to the first firmware I ever flashed which is 1.18.168 and it still made no difference. It still uses the same blob for WiFi and it used to work well. I have no clue what's going on, any reflashing or erasing or trying out previously proven settings seems to just fail.

[MaxineMuster]

Just poking around in the dark:
I remember setting static IP with LN882H was a bit strange, so could you try if trying with DHCP IP makes any difference?

[bausensi]

Just poking around in the dark: I remember setting static IP with LN882H was a bit strange, so could you try if trying with DHCP IP makes any difference?

Static IP or DHCP makes no difference. I've tried both methods and they both end up in a loop. Is there an uncovered edge case in OpenBeken or something? After all, the blob is poorly documented. This situation sucks, I was enjoying my little cheap bulb and having warm and cool white on demand.

´[WLIB_I]auth to 2´
´[WLIB_I]wifi sw subsystem result: 2´
´[WLIB_I]Reinitiating Scan.´

[divadiow]

Erasing the flash and changing the MAC address didn't fix the issue.

just curious about how erasure was performed. was it in the official tool?

[bausensi]

Erasing the flash and changing the MAC address didn't fix the issue.

just curious about how erasure was performed. was it in the official tool?

I used the LN882H CMD Flash Tool, it seemed good enough but i'll try the official one soon.
EDIT: Somehow it got "bricked", now the UART loops at "Welcome to OpenBeken for the LN882H" after erasing and reflashing with the official tool. Any way to get out of this? I flashed at 2M and then at 115200 baud and the result is the same.
EDIT 2: The boot finished after a few minutes! The UART is reporting more output now!
EDIT 3: Found the problem: my new FT232RL serial adapter's 3.3V regulator can't sustain the entire bulb module's operation when WiFi is enabled unlike my now bad FT232H module, so whenever it tries to enable networking the 3.3V line will sag causing the device to constantly reset. Eventually I managed to flash it and test it on the wall socket. Sadly I'm back at square one after getting the flash done, since it still doesn't work even after erasing and reflashing with the official tool. Only works on AP mode and station mode can't join my local network like it used to do. I'm lost.

[bausensi]

This issue is very strange. WiFi successfully connected in station mode using someone else's Tuya firmware dump. They might use a different approach towards storing WiFi connection data. Documentation for LN882H also seems to be very poor. At this point I'm considering bricking the LN882H and soldering an ESP8266 module to take over the board instead.