FAQ 
TL;DR: For 5 OpenBeken BK7231N/CB2S switches, “same SSID+Password” worked on a phone hotspot but failed on a Fritz!Box router; the fix was resetting 3 Fritz!Box mesh repeaters and rebuilding the mesh. This FAQ helps smart-switch users diagnose correct-credential WiFi failures after flashing. [#20593364]
Why it matters: Correct SSID and password do not prove the router, mesh, RF data, or scan path is healthy.
| Alternative |
Result in the thread |
Key difference |
| Phone hotspot |
Connected |
Same SSID Bernd, password 12345678, channel 6 in one test |
| Fritz!Box guest WiFi |
Failed |
Same SSID and password, scan returned get_scan_rst_null |
| Rebuilt Fritz!Box mesh |
Connected |
3 Fritz!Box devices reset and re-added to mesh |
Key insight: If OpenBeken connects to a hotspot but not to a Fritz!Box using identical credentials, investigate the router or mesh before scrapping the BK7231N module.
Quick Facts
- The failing device used a CB2S module with a BK7231N chip, and the user had a 2 MB original firmware backup before flashing. [#20581033]
- The UART log showed
WIFI_STA_AUTH_FAILED - 3 after sm_deauth_handler reason=1, even though the SSID and password appeared correctly. [#20578696]
- The working hotspot log reached
WIFI_STA_CONNECTED - 4 and received IP 192.168.133.113 with gateway 192.168.133.223. [#20581859]
- The router-side failure showed
get_scan_rst_null and RL_STATUS_STA_SCAN_VAIN, meaning the scan returned no matching AP result. [#20581859]
- The final fix was rebuilding a mesh of 3 Fritz!Box devices; after that, all OpenBeken devices connected normally. [#20593442]
Why does an OpenBeken BK7231N smart switch show the correct SSID and password in the UART log but still fail to connect to WiFi?
The SSID and password can be correct while the device still fails at scan, authentication, or router mesh handling. In the first log, OpenBeken printed the SSID and key, then reached
WIFI_STA_AUTH_FAILED - 3. Later tests proved the same credentials worked on a phone hotspot. The router mesh, not the typed password, caused the final failure. The user fixed all devices by resetting 3 Fritz!Box mesh nodes and rebuilding the mesh.
[#20593364]
How do I use the BK7231GUIFlashTool Restore RF button after flashing OpenBeken on a BK7231N or CB2S module?
Make a 2 MB flash backup first, then use Restore RF in BK7231GUIFlashTool.
- Create a full 2 MB backup in the flasher.
- Flash OpenBeken, then press
Restore RF.
- If needed, restore the original backup or test Tuya again.
The thread expert warned that the backup lets you return to the original version. Restore RF did not solve this case, but it solves similar reports. [#20578737]
What does the OpenBeken log message WIFI_STA_AUTH_FAILED mean on a BK7231N smart switch?
WIFI_STA_AUTH_FAILED means the station tried to join WiFi but failed during authentication or association. In the first log, it followed
sm_auth_send:1, repeated
sm_deauth_handler reason=1, and
SM_CONNECT_IND_fail. The failure appeared at status code
3. This does not prove the password is wrong, because the same device later connected to a phone hotspot with valid WPA2 credentials.
[#20578696]
What does get_scan_rst_null mean in BK7231N WiFi logs when connecting to a Fritz!Box router?
get_scan_rst_null means the BK7231N scan returned no usable result for the target SSID. The thread expert interpreted it as “no AP of given SSID was found.” In the failing Fritz!Box guest WiFi log,
get_scan_rst_null appeared with
RL_STATUS_STA_SCAN_VAIN. In the working hotspot log, the same point showed
wpa_get_scan_rst:1, then association succeeded.
[#20582079]
How can a Fritz!Box WiFi Mesh setup prevent OpenBeken BK7231N devices from connecting while ESP/Tasmota devices still work?
A misconfigured Fritz!Box mesh can block OpenBeken BK7231N scanning or association while ESP/Tasmota still connects. The user had 3 Fritz!Box units in a mesh and saw OpenBeken fail against the router. ESP/Tasmota devices had no connection problem. After resetting all repeaters and adding them back to the mesh, all OpenBeken devices connected. The exact mesh fault was not identified.
[#20593364]
What WiFi settings should I check on a Fritz!Box when OpenBeken connects to a mobile hotspot but not to the router?
Check 2.4 GHz mode, WPA2 security, MAC filtering, channel, SSID, password, and mesh state. The thread tested WPA2 on both networks, disabled MAC filtering, tried the same SSID
Bernd, and used password
12345678. It also compared router channel settings with the phone hotspot. The final fix was not a password change; it was rebuilding the Fritz!Box mesh.
[#20581859]
How do I troubleshoot OpenBeken devices that connect to a phone hotspot but fail on a WPA2 2.4 GHz router network?
Treat the phone hotspot as proof that the module and firmware can work. First, copy the same SSID and password to the router. Second, verify 2.4 GHz, WPA2, channel, and MAC filtering. Third, rebuild router mesh or test another router. In the thread, the same SSID and password worked on a phone but failed on Fritz!Box until 3 mesh devices were reset.
[#20585638]
What is a CB2S module, and how is it related to the BK7231N chip used in Tuya smart switches?
A CB2S module is the small WiFi module inside the smart switch that carried the BK7231N chip in this case.
“CB2S is a WiFi module that hosts the BK7231N chip, providing the wireless microcontroller platform used by some Tuya smart switches.” The user identified the module as CB2S and had made an original firmware backup before flashing OpenBeken.
[#20581033]
What is RF calibration data or Restore RF in BK7231 flashing, and why can losing it break WiFi connectivity?
RF calibration data stores radio-specific settings, including values tied to WiFi operation and MAC handling.
“Restore RF is a flasher function that restores radio-frequency calibration data, preserving device-specific wireless settings after erase or flash operations.” The expert suggested Restore RF after a 2 MB backup. He also warned that clearing flash without restoring RF can cause MAC-related problems.
[#20581702]
What is UART logging, and how can it help diagnose OpenBeken WiFi connection failures?
UART logging is serial output from the device that exposes boot and WiFi driver messages.
“UART logging is a serial diagnostic method that reads startup and runtime logs through UART pins, showing scan, authentication, DHCP, and WiFi status transitions.” In this thread, UART 2 revealed
WIFI_STA_AUTH_FAILED,
get_scan_rst_null, and the working IP
192.168.133.113.
[#20578696]
What is WPA2, and which WPA2 router settings can affect BK7231N or Tuya smart switch connectivity?
WPA2 is the WiFi security mode used on both tested networks.
“WPA2 is a WiFi security standard that authenticates clients and encrypts traffic, but router implementation, MAC filtering, band, channel, and mesh behavior can still affect joins.” The thread checked WPA2 on phone and router, verified 2.4 GHz, and ruled out MAC filtering. Mesh reset fixed the issue.
[#20586420]
What is a WiFi mesh network, and why can resetting Fritz!Box repeaters fix smart home device connection problems?
A WiFi mesh network uses multiple access points under one coordinated network name.
“A WiFi mesh network is a multi-node wireless setup that extends coverage by coordinating routers or repeaters, while presenting one roaming network to clients.” In this case, 3 Fritz!Box mesh devices had a bad state. Resetting the repeaters and reconnecting them to the mesh restored OpenBeken connectivity.
[#20593442]
OpenBeken vs Tasmota on smart switches: which is better for BK7231N, CB2S, and ESP-based modules?
Use OpenBeken for BK7231N/CB2S modules and Tasmota for ESP modules. The thread used OpenBeken on CB2S with BK7231N. The user already had ESP/Tasmota devices that connected without trouble. The expert also noted that replacing CB2S with an ESP module was possible, which would enable Tasmota instead of OpenBeken.
[#20581040]
How can I replace a CB2S BK7231N module with an ESP module for Tasmota in a smart switch?
Replace the CB2S only if you can map power, relay, button, LED, and sensor pins safely. The thread expert said a CB2S could be replaced cheaply with an ESP module. The user had already considered ESP and Tasmota. The thread did not provide wiring diagrams, voltage values, or pin mappings for the replacement, so use the original backup and board tracing before removal.
[#20581040]
How do I configure pins for switches, relays, LEDs, and a BL0942 power sensor on an Aubess mini power monitor switch in OpenBeken?
Configure each OpenBeken pin by matching the Aubess switch functions to relay, switch, LED, and BL0942 roles. The thread confirms the device was an Aubess mini power monitor switch and that the switches plus BL0942 power sensor were eventually working. It does not list the exact GPIO map. Use UART logs and board tracing to verify every pin before applying mains power.
[#20593364]
AI summary based on the discussion. May contain errors.
