How to prevent Windows automatic reconnection

RE: How to prevent Windows automatic reconnection

Federico — Tue, 05 Sep 2023 13:50:32 GMT

Hi susheel,

Thanks for the answer! Your workaround might work for this specific case with the Glucose example, but our system always has the "allow_repairing" flag in true, and we still see this behavior from time to time, and in such cases erasing the bond info has no effect.

Is there anyway to prevent an external device from spamming with connection attempts? We've tried the blacklist but it's not exactly what we're looking for, because the external device connects and then it's kicked out. This still consumes resources on the nRF side. We'd like a way to ignore the connection requests from a given MAC address, for example. Is this possible?

Thanks!

RE: How to prevent Windows automatic reconnection

Susheel Nuguru — Mon, 21 Aug 2023 12:11:42 GMT

I think the main issue here is that when you delete the bond information in the windows, the bond information in the nRF device still remains. When the windows device is trying to connect to your glucose device again, windows wants sees this device as new (since we removed the pairing information). But to the nRF Glucose device, which did not delete its bond information, it sees the windows machine as a trusted paired device. This is causing both the devices to act differently.

When you remove the pairing information in the windows, you should somehow communicate this to the nRF device and call delete_bonds(). In the Glucose example, we can delete the bonds in the nRF when you reboot the chip while pressing button 4 (delete bonds button).

So try to reproduce the issue again with the steps you mentioned and after that reboot the nRF device with button 4 pressed. That will erase the bond info on nRF as well and both devices now see each other as untrusted and initiate meaningful procedures to gain trust. So you should find a suitable place in your application where you call delete_bonds(); when the Windows delete its bond information (maybe in the disconnected event based on the disconnect reason)

RE: How to prevent Windows automatic reconnection

Susheel Nuguru — Fri, 18 Aug 2023 08:11:55 GMT

Federico, Most of us are back from Summer vacation on Monday, sorry for the delays it caused. I will try to reproduce this on Monday. It is not usual in normal (non holidays) period that we take this time reproduce. I appreciate your patience. You will hear from me early next week on my observations.

RE: How to prevent Windows automatic reconnection

Federico — Tue, 15 Aug 2023 14:10:59 GMT

Hi Susheel, do you have any updates? Thanks!

RE: How to prevent Windows automatic reconnection

Susheel Nuguru — Thu, 10 Aug 2023 12:50:09 GMT

I am sorry for delays Federico, I did not manage to work on reproducing it this week. I will be away for a week and will request one of my colleagues to see if they can reproduce it.

RE: How to prevent Windows automatic reconnection

Federico — Mon, 07 Aug 2023 14:09:48 GMT

Hi Susheel,

Just to post a few updates. We were able to narrow down a couple of things:

1) All our issues can be reproduced with the Glucose example from the SDK17

2) To reproduce issue 1) from the OP, just search for bluetooth devices from the Bluetooth window, pair and wait for the status to change from "Connected" to "Paired". Then press "Remove Device". You can see on the nRF log that windows triggered a connection and pairing. It's not obvious on the PC because this pairing has actually failed. To see the user prompt, modify the Glucose example to "allow_repairing=true". This will cause a pop-up to show on the PC when removing. This does not happen for other BLE devices, how could we prevent this? What triggers this?

3) We were also able to reproduce the connection loop on Windows. It's fairly simple actually, just pair with the Glucose example as-is, with allow_repairing in FALSE. Then remove the device and then pair again. The nRF will refuse the pairing and windows will keep on reconnecting, and failing, in the background, non-stop. This looks like a windows bug really, but is there anything we can do to prevent this? We can set allow_repairing to TRUE, but it looks like other errors during a pairing sequence will trigger this as well, so it's not a complete solution. The black list doesn't really solve it, it will just kick the PC out but it's still taking up resources for a while. This behavior is really taxing on our system from the point of view of power draw and connection availability to other devices. Is there anything we can do?

We're working on Windows 10 with integrated Intel BLE/Wifi chips.

Thank you!

RE: How to prevent Windows automatic reconnection

Susheel Nuguru — Fri, 04 Aug 2023 11:26:25 GMT

We were a bit understaffed due to summer holidays, Sorry for the late reply,
I got assigned to this case and will respond to your queries at most on Monday. Thanks for your patience.