BLE Addr changed and won't reconnect

[ratmice]

I seem to have an issue where gadget bridge will no longer reconnect to my bangle.js,
for a while it seemed like it wouldn't reconnect at all, but then I noticed that the ble address
had changed. So I went through the process of adding a new device with the new address.

Whenever I try to connect manually it does appear to connect, but never stays connected very long,
and never automatically connects.

The address appeared to change randomly without doing any firmware updates, after updating to the latest it seems to have the same behavior.

One of the weird things about the BLE addr, is if I look at the info tab in the Bluetooth Manager app on linux, it lists the old ble addr. While it lists the new ble addr on the list of devices. So I'm a little bit confused. I guess one thing worth noting is I had installed the Bluetooth Heart rate Monitor app, which opens up another gatt.. Interestingly if I remove that app, and do a scan on linux
the device list/info tab both show the old bluetooth address. (Gadgetbridge on android still seems to only connect to the new address, which I don't see from linux)

Perhaps the reconnect issue is also caused by updating android...
Anyhow curious if anyone has experienced anything like that before.

[gfwilliams]

if I look at the info tab in the Bluetooth Manager app on linux

The Bluetooth Manager will (afaik) show any device it's seen whether in range or not, so if your address did change it'd still show the old one as well.

What if you use the NRF Connect app on Android? What address does that see?

I'm pretty confident that the only way the Bangle would actually change its MAC address is if the NRF.setAddress command was called on it. You wouldn't have uploaded any code with that would you?

The only app I can see that does it is openhaystack (the one that turns your Bangle into an iBeacon

[ratmice]

@joserebelo In the "General settings", I see "Start automatically" (on), "Connect to Gadgetbrige device(s) when Bluetooth is turned on" (on), and "Reconnect only to connected devices" (on), but nothing related to reconnect automatically.

Can confirm that if I go to:
"Android settings" -> "Apps" -> "Bangle.js Gadgetbridge" -> "App battery usage" -> "Allow background usage", -> "Allow Background usage" -> "Unrestricted" is selected.

When that is not selected I usually see some error pop-up about background processes, but I haven't been seeing that error, at times though the android upgrade process has reset that setting, it didn't appear to this time.

[joserebelo]

@ratmice I mean these settings:

Then scroll down to "Connection".

[ratmice]

So many settings menus, I didn't know about that one, however "Auto reconnect to device" is selected.

[ThomasKuehne]

Android 15 and 16 signifficantly changed some BT implementation details that are now more likely to hit race conditions in GB. Fixing them is work in progress. As a workaround you could disable the general "Settings / Discover and Pairing options / Reconnect on BLE scan" and device specific "Connection / Connect on connect to device". This only reduces but doesn't eliminate race conditions.

[ratmice]

Yeah, that is kind of what I had figured, it was mostly the random bluetooth address change that threw me for a loop since I only noticed these two things at the same time.

[lunctis-viribus]

I have exactly the same issue as @ratmice. When disconnected my Bangle.js 2 does not reconnect automatically at anytime, only when I (re)connect manually it works. Background usage is set to allowed. Also Auto reconnect to device is enabled.
My first guess is indeed as @ThomasKuehne says it's related to Android 16.
It's quite an annoying bug!

[ratmice]

Marking the answered by @ThomasKuehne I'm not certain this is fully fixed, but with the latest released of the bangle.js gadget bridge app with his fixes the frequency of issues has been reduced to where I have not encountered any issues in the last week or so.

[gfwilliams]

Thanks! I've 0.86.1b on the Play Store has these changes, and I've just pushed it from 'Open Testing' to a release so it should start rolling out to everyone in a few days

[thyttan]

I'm having strange issues with pairing since some weeks now. I wonder if it's related. I've wanted to do a proper bug report to espruino/Espruino but haven't found the time.

My problems is partially described in the notes of this comment on the Gadgetbridge repo: https://codeberg.org/Freeyourgadget/Gadgetbridge/pulls/4849#issuecomment-4989093

[thyttan]

The way to get pairing to work again for me has been to reflash the firmware from the app loader one or several times. Eventually it started to work again temporarily. The problem has kept coming back though.

[gfwilliams]

Maybe try long-press rebooting into the recovery menu next time? That's enough to clear out pairing data stored in Bangle.js.

I guess you're on some kind of nightly Gadgetbridge build? It's perhaps not a coincidence that I updated the Play Store Gadgetbridge just a few days ago and that's when @ratmice started having problems?

[thyttan]

Maybe try long-press rebooting into the recovery menu next time? That's enough to clear out pairing data stored in Bangle.js.

I believe I tried that without success. Will give it another try sometime.

EDIT: Tried going to the recovery menu now. It seems like it cleared pairing info. A notification dialog with a pairing request from the Bangle then appeared on my phone and I chose to "Pair & connect" - but it didn't seem to succeed (I didn't notice the notification until after ca 40 mins so that may be why). Gadgetbridge seemed to still be connect to the Bangle even though the pairing was gone. (I'm now using a different phone from the one I used before and this is not in regards to the same problem I had when starting this thread. It's mainly a note to say unpairing when entering recovery seems to work like it should.)

[ThomasKuehne]

@ratmice

Whenever I try to connect manually it does appear to connect, but never stays connected very long,
and never automatically connects.

Could you please share a GB log of connect -> connected -> disconnected ?

[ratmice]

Will do the next time it occurs, I think though that as you mentioned previously those settings you mentioned have reduced the frequency of the race condition

[ratmice]

I went ahead and sent the log to the address listed on your git commits, hope that is alright.

[ThomasKuehne]

The log shows two concurrent connection initializations starting 19ms appart. That is causing at least part of the issue.

Not yet fixed in the GB's master branch but should no longer be possible with https://codeberg.org/Freeyourgadget/Gadgetbridge/pulls/4916 . Please note that 4916 is likely OK for all GATT devices including Bangles but will almost certainly fail to reconnect some other devices.

[gfwilliams]

That's great, thanks! I'll keep an eye on that and will try and get a new Play Store release out when it's merged