BLE connection to paired device failed after some time.

RE: BLE connection to paired device failed after some time.

Edvin — Wed, 15 Oct 2025 07:01:35 GMT

Hello,

Sorry for the late reply.

To me, the failing connection attempts just seems like the GoPro doesn't pick up the CONNECT_IND packet (packet 247 in the connection_failed.pcapng), and hence, the central is not able to connect. So if this is, as you describe, happening at all connection attempts when the issue first occurs, then you need to reach out to GoPro. It sounds like they are using a filter accept list, and your device for some reason is not on that list. Whether that is actually what happens, I can't tell just from a sniffer trace. It is either a bug in the GoPro application, or it is intentional from GoPro,, but there is nothing in the trace indicating that you shouldn't be able to connect to it.

Best regards,

Edvin

RE: BLE connection to paired device failed after some time.

D233374 — Wed, 08 Oct 2025 18:17:52 GMT

Today it stopped connecting again. I recorded a Wireshark log.
But it looks like the problem is on the GoPro side. I found a discussion of a similar issue on their GitHub.
The only strange thing is that I have no problems connecting my phone or laptop, which use the same OpenGoPro API.
Attached are three logs: pairing, successful connection of an already paired device, and unsuccessful connection.

Paring:

devzone.nordicsemi.com/.../3542.pairing.pcapng

Connection susccess:

devzone.nordicsemi.com/.../8322.connection_5F00_success.pcapng

Connection failed:

devzone.nordicsemi.com/.../4213.connection_5F00_failed.pcapng

RE: BLE connection to paired device failed after some time.

Edvin — Mon, 06 Oct 2025 10:34:54 GMT

Also, perhaps reach out to GoPro, and ask if they have seen something similar before? That their devices stops responding to familiar devices at some point.

Best regards,

Edvin

RE: BLE connection to paired device failed after some time.

Edvin — Mon, 06 Oct 2025 10:34:18 GMT

If you actively change the address, I would expect it to fail. The question is if the nRF or the GoPro changes address using the same identity, it should be able to detect the address change using the identity resolving key (IRK). But if you set a new random address, that new address would not be resolvable.

Using either the existing connection (or create a new one if you deleted the bonding information of your devices, can you capture a connection while it is still working, and then a new one when it fails?

Best regards,

Edvin

RE: BLE connection to paired device failed after some time.

D233374 — Fri, 03 Oct 2025 13:29:46 GMT

I did a little experiment. After pairing and connecting successfully, I changed the NRF address. As expected, the connection failed. But the error was different:

[00:00:01.046,936] <wrn> gopro_discovery: Security failed: C6:EA:FE:77:84:76 (random) level 1 err 2 BT_SECURITY_ERR_PIN_OR_KEY_MISSING

Whereas with the connection problems described in the original message, the error:

[00:00:01.094,787] <wrn> bt_conn: conn 0x200037e0 failed to establish. RF noise?

[00:00:01.095,275] <wrn> gopro_discovery: Security failed: C6:D9:69:8A:22:91 (random) level 1 err 9 BT_SECURITY_ERR_UNSPECIFIED

Perhaps the problem is not in the nRF address.

RE: BLE connection to paired device failed after some time.

D233374 — Fri, 03 Oct 2025 11:34:39 GMT

I did the following:
- added creating a static address from hw info and printing the address to debug (bt_id_create() before bt_enable() )
- erased the contents of the NRF flash memory with the saved settings
- erased the connection settings on the GoPro
- recorded a connection dump with pairing
- recorded a successful connection dump
At the moment, the NRF successfully connects to the GoPro. If problems arise again, I can record a connection dump.

Pairing dump:

devzone.nordicsemi.com/.../0636.pairing.pcapng

Successful connection dump:

devzone.nordicsemi.com/.../connection_5F00_success.pcapng

RE: BLE connection to paired device failed after some time.

Edvin — Fri, 03 Oct 2025 08:07:23 GMT

Just in case GoPro does anything proprietary, did you follow this step after pairing:

https://gopro.github.io/OpenGoPro/ble/protocol/ble_setup.html#wait-for-camera-ble-readiness

"In order to verify readiness, the client shall continuously poll Get Hardware Info until it returns a success status."

Perhaps the gopro doesn't acknowledge the central if it doesn't do this.

You can also try to capture a sniffer trace of a new connection (including pairing/bonding) with a working device, to see if this does something your nRF app doesn't do.

Best regards,

Edvin

RE: BLE connection to paired device failed after some time.

Edvin — Fri, 03 Oct 2025 07:52:58 GMT

Can you please try to capture a sniffer trace from a successfull connection, and then a new sniffer trace later, when the nRF tries to connect, but is not able to?

Does the nRF change it's BLE address between these two events? It shouldn't really matter, as long as they are bonded, but it may be a bug in the GoPro FW.

The fact that when this issue first occurs, it doesn't reconnect until the gopro is put in pairing mode again, suggests that it isn't just a packet loss. The GoPro probably dropped the nRF from it's whitelist for some unknown reason. Can you please check the address of the nRF, whether it changes between a working connection and the later stage where it doesn't work?

Best regards,

Edvin

RE: BLE connection to paired device failed after some time.

D233374 — Thu, 02 Oct 2025 20:31:17 GMT

[quote userid="26071" url="~/f/nordic-q-a/124754/ble-connection-to-paired-device-failed-after-some-time/550505"]If you reset/power cycle the nRF after it fails to connect, will it be able to reconnect as normal then? If not, what does it take for you to be able to connect again? Or do you need to put the gopro in pairing mode for that to work?[/quote]

I only need to put gopro in pairing mode. Reset/power cycle nRF or GoPro doesn't change anything.

[quote userid="26071" url="~/f/nordic-q-a/124754/ble-connection-to-paired-device-failed-after-some-time/550505"]s the GoPro connected to any other devices in the meantime, before it stops working? Is it reset between the two connection attempts in 1685 and 1755 in the sniffer trace?[/quote]

I have four devices that connect to my GoPro:
- remote control
- phone
- laptop
- NRF
The problem only occurs with my NRF device.
I debug the device on a table and then test it in the car. Sometimes the connection would work on the table, but then stop working in the car. Between these events, there were no other connections to the GoPro.
I had doubts about the car's power supply, but powering it from a separate battery didn't solve the problem. The interference idea also didn't work—if the NRF stops connecting, it won't connect anywhere else.

No, no other devices connected between these two connection attempts, and the GoPro didn't reboot.

[quote userid="26071" url="~/f/nordic-q-a/124754/ble-connection-to-paired-device-failed-after-some-time/550505"]And a key question, does continue scanning after the failed connection attempt?[/quote]

I set a 3-second delay between connection attempts to avoid spamming the GoPro.

As you can see from the debug output, after the connection fails, there is a 3 second pause and then the scanning and connection process starts again. This happens endlessly with the same result.

[00:00:00.549,133] <inf> gopro_discovery: Scan started

[00:00:00.680,175] <dbg> gopro_discovery: scan_filter_match: Filters matched. Address: C6:D9:69:8A:22:91 (random) connectable: 1

[00:00:00.843,566] <inf> gopro_discovery: Connected: C6:D9:69:8A:22:91 (random)

[00:00:00.843,688] <inf> gopro_discovery: Change security

[00:00:00.844,177] <err> gopro_discovery: Stop LE scan failed (err 0)

[00:00:01.094,787] <wrn> bt_conn: conn 0x200037e0 failed to establish. RF noise?

[00:00:01.095,275] <wrn> gopro_discovery: Security failed: C6:D9:69:8A:22:91 (random) level 1 err 9 BT_SECURITY_ERR_UNSPECIFIED

[00:00:01.095,367] <wrn> gopro_discovery: MTU exchange failed (err 14)

[00:00:01.095,520] <inf> gopro_discovery: Disconnected: C6:D9:69:8A:22:91 (random), reason 0x3e

[00:00:01.095,794] <dbg> gopro_discovery: disconnected: Pause for 3 sec

Next attempt:

[00:00:04.096,008] <dbg> gopro_discovery: scan_work_handler: Scan start

[00:00:04.096,130] <dbg> gopro_discovery: try_add_address_filter: Saved bond found: C6:D9:69:8A:22:91 (random)

[00:00:04.096,221] <inf> gopro_discovery: Address filter added: C6:D9:69:8A:22:91 (random)

[00:00:04.097,076] <inf> gopro_discovery: Scan started

[00:00:04.455,474] <inf> gopro_discovery: Connected: C6:D9:69:8A:22:91 (random)

[00:00:04.455,627] <inf> gopro_discovery: Change security

[00:00:04.456,085] <err> gopro_discovery: Stop LE scan failed (err 0)

[00:00:04.706,542] <wrn> bt_conn: conn 0x200037e0 failed to establish. RF noise?

[00:00:04.706,878] <wrn> gopro_discovery: Security failed: C6:D9:69:8A:22:91 (random) level 1 err 9 BT_SECURITY_ERR_UNSPECIFIED

[00:00:04.706,970] <wrn> gopro_discovery: MTU exchange failed (err 14)

[00:00:04.707,153] <inf> gopro_discovery: Disconnected: C6:D9:69:8A:22:91 (random), reason 0x3e

[00:00:04.707,275] <dbg> gopro_discovery: disconnected: Pause for 3 sec

Next attempt:

[00:00:07.707,489] <dbg> gopro_discovery: scan_work_handler: Scan start

[00:00:07.707,611] <dbg> gopro_discovery: try_add_address_filter: Saved bond found: C6:D9:69:8A:22:91 (random)

[00:00:07.707,702] <inf> gopro_discovery: Address filter added: C6:D9:69:8A:22:91 (random)

[00:00:07.708,740] <inf> gopro_discovery: Scan started

[00:00:07.918,243] <dbg> gopro_discovery: eir_found: Camera ON, connecting

[00:00:08.072,906] <inf> gopro_discovery: Connected: C6:D9:69:8A:22:91 (random)

[00:00:08.073,028] <inf> gopro_discovery: Change security

[00:00:08.073,516] <err> gopro_discovery: Stop LE scan failed (err 0)

[00:00:08.324,218] <wrn> bt_conn: conn 0x200037e0 failed to establish. RF noise?

[00:00:08.324,615] <wrn> gopro_discovery: Security failed: C6:D9:69:8A:22:91 (random) level 1 err 9 BT_SECURITY_ERR_UNSPECIFIED

[00:00:08.324,707] <wrn> gopro_discovery: MTU exchange failed (err 14)

[00:00:08.324,859] <inf> gopro_discovery: Disconnected: C6:D9:69:8A:22:91 (random), reason 0x3e

[00:00:08.324,981] <dbg> gopro_discovery: disconnected: Pause for 3 sec

[quote userid="26071" url="~/f/nordic-q-a/124754/ble-connection-to-paired-device-failed-after-some-time/550505"]I assume you don't have any debug access on your GoPro, right?[/quote]

Of course, I don't have access to debugging the GoPro.

RE: BLE connection to paired device failed after some time.

Edvin — Thu, 02 Oct 2025 13:58:48 GMT

Hello,

If you reset/power cycle the nRF after it fails to connect, will it be able to reconnect as normal then? If not, what does it take for you to be able to connect again? Or do you need to put the gopro in pairing mode for that to work?

From your sniffer trace it looks like the GoPro/peripheral either misses the CONNECT_IND packet at 1685 and 1755, or it is ignored (if the peripheral is using a filter accept list/whitelist).

Is the GoPro connected to any other devices in the meantime, before it stops working? Is it reset between the two connection attempts in 1685 and 1755 in the sniffer trace?

And a key question, does continue scanning after the failed connection attempt?

I assume you don't have any debug access on your GoPro, right?

Best regards,

Edvin