Pairing with bonded peer GATT ERROR 0x85 (133)

[k.szpila]

Hi,

I want to use filtered list during BLE advertisement in out project. The flow is as follows:

(I'm using nRF connect app for testing ble connection)

1. Just advertise so any device can be paired.
2. Bond (from now on whenever device disconnects advertise with enabled filtered list)
3. Now i can disconnect as many times as i want, and connect using devices remembered in bonded tab.
4. If i reboot the device the bond is still remembered but any pairing attempt results in immediate error log in the nRF app
```
Error 133 (0x85): GATT ERROR
```
5. Now i can try again with another device, but the pairing using remembered bond works until next reboot.

I'm using:
nrf-sdk 1.8.0 with Zephyr v2.7.0-ncs1

[Simonr]

Hi

Error 133 (0x85) is just a generic disconnect error that don't tell us too much of what is going on here I'm afraid. But I do see that the "autoConnect" seems to be set to false, which might be a pointer to what's going on. 

What phone, specifically? Are you able to recreate this issue no matter what phone you use as a central? It might help doing a sniffer trace of the connection, to see the data transmitted over the air. If you have a spare nRF52 DK you can use Wireshark and the nRF Sniffer to do so for example, or a dedicated BLE sniffer if you have one of those.

Best regards,

Simon

[k.szpila]

Hi,

Here is a log from Whireshark:
drive.google.com/.../view

The scenario is identical as previously:

1. Pair with the device

2. Create bond

3. Click disconnect in nrf-connect app.

4. Restart device

5. Try to connect with using bond

Best regards,
Karol

[Simonr]

Hi Karol

From the sniffer trace the disconnect seems to be caused by the peripheral (nRF device) after the connection parameter update for some reason (packet 1704 returns "Remote User Terminated Connection" from the central). You will need to debug on the peripheral side to find out why it disconnects, I think you should see a more descriptive disconnect reason by debugging the nRF device. It seems to connect and encrypt the connection as expected, but there's no specific info on what's causing the disconnect.

Best regards,

Simon