I’m having an issue with the Tandem mobile app (Android) constantly losing connection with the pump. The only work around was turning off my phones Bluetooth and turning it back on and then the app would connect with the pump. It is a PIA and basically makes the mobile app unusable. My pump is updated to the current version (7.10.3) and I have deleted and reinstalled the mobile app. Neither seem to resolve my issue.
Is anyone else having this issue?
I use the Mobi pump with iPhone. I do have this issue periodically but most of the time it is short lived. In the 16 months I have been using Mobi, I have only had to toggle Bluetooth once or twice. Not frequent enough for me to be concerned. I hope you’re able to resolve this soon. Have you reached out to Tandem? I have found their Clinical/Tech Support to be very responsive
@jim26 a couple of years ago I ran into a similar issue, not with Tandem, but with Bluetooth. It appears that there were (maybe still are) connection issues when there are too many potential Bluetooth connections in your Android phone.
The way I resolved my problem:
I wonder if this might impact your problem?
Good idea, I will play around with that. I did delete the Tandem connection and paired again, but I do have several other connections for other devices that I can play with.
It seems the problem is once it disconnects, it will never connect again.
Bluetooth itself only supports a small number of connections at once, there’s a discussion here:
The maximum depends on the chip used, but 32 is high:
Fundamentals - Connections | Connections | Bluetooth LE | v10.1.1 | Silicon Labs.
However notice that this is talking about bluetooth connections, not paired devices and not devices in the environment. This screen shot from my 'phone might help:
There is only one connected device (the Cambridge Audio amplifier at the top showing “In use”) and I had to connect it manually for the purpose of that screen shot; normally my 'phone doesn’t have any connected devices. The two G7s don’t show as connect because they only connect for a short time every five minutes (stare at the screen long enough and I might see it happen!) The Avantree (my car stereo system) and the EONON (my wife’s) connect automatically (even if I’m not in the car!)
So the first thing to check is whether the Tandem pump is continuously connected; it almost certainly will not be because that requires battery. Then check the other entries to see if there are more than three or four things which are connected all the time. Depending on the 'phone that might interfere with the pump if the pump is using a Bluetooth mechanism where the connection isn’t always-on; even if the 'phone isn’t out of connections it seems to take signifcant time in the app to manage the connection setup.
If the app is connected to the pump all the time it might be getting locked out somehow, but I really wouldn’t expect that for a device, particularly a CGM, that gives regular updates.
I do know that the G7 uses a particular BLE protocol and is not connected except for the 5 minute update. If the Tandem does the same thing the 'phone has to wake up, notify the app and then the app has to look at the incoming connection and decide if it is one it wants. If there are several apps doing that at once that could cause a problem as a result of overall delays.
It’s worth checking Settings/Battery, this displays a list of battery use by app:
AAPS is my pump controller; it’s controlling my Omnipod, xDrip+ is my CGM receiver, so together they are doing the same as the t:slim app. The AAPS battery usage is way over the top, I don’t know why, but it is doing bluetooth to the Omnipod (regularly, every few minutes) and WWW to tidepool. If there is something else in there, or several things, which are using a lot of battery they will probably also be using a lot of network and that can cause problems. If I find an app like that I remove it from the 'phone.
The other thing to check is the “paired device” list. Audio devices should be ok because the auto-pair is, I believe, handled internally by Android (so it’s fast), but if there is something there which auto-pairs and is not audio that might be a problem (I’m BSing here). If there is something like the Dexcom (DXCM in my list) which does not attempt to “connect” if clicked on, just takes you to the (i) settings for the device, then I believe there has to be an app to handle the connection so that might be a problem.
In my list:
o DXMC?? both these are handled by xDrip+, note the “bluetooth” icon at the left.
o Contour78… my Contour USB fingerstick meter, also handled by Dexcom, same bluetooth icon.
o Avantree, Cambride Audio, Jabra, EONON; all audio devices, handled by Android.
o Flipper, a Flipper Zero, handled by the Flipper app (which I have never got to work…) Also has the bluetooth icon.
So a quick check might be to look for paired devices which have the bluetooth icon and check you know what they are.
Thanks, good info. I have relatively few devices paired with my phone (watch, Dexcom, Tandem, Car and my headphones.)
I should of looked at the Google play store as this is a very common complaint. So must be more of Tandem issue with their app and Android. Frustrating.
I get this issue every couple days. In previous versions it would be multiple times a day, so it has improved for me. 
Switching the Bluetooth off then on again is my fix too.
To make it a little less of a PIA, I rearranged my quick settings tiles to put Bluetooth right at the top. On Android, I just have to tap the pencil at the bottom to adjust what shows up where.
Adding emphasis:
You pair both, so they may be competing for their individual hookup at the same time. The Dexcom app will pair reliably on the 5 minute interval when the Gx starts its bluetooth broadcast, the t:slim does the same thing. You quote the results from the t:slim app but to update those the t:slim has to initiate, or maybe just use, a connection with the Tandem app in the 'phone immediately after it gets the CGM reading.
Try removing the Dexcom app from your 'phone and see if that helps.
@jim26 I’m having the same issue. As a work around, I go to Apps/Tandem TSlim then apply “ Force Stop” application. At that point I go straight into the app and I have zero issues for a few days.
Not perfect or elegant, but it works, it’s quick, and it’s effective.
Is the t:slim visible (anywhere) in “Settings/Bluetooth”?
Yes, it reads “TSlim X2*****”. However, I have never made any effective Bluetooth changes thru the phone BT other than off/on. The pairing between the app and phone seems to be fairly locked down.
Below is my BT list…
Oooh, I hate Android. “Saved” on your 'phone means “Paired” on mine and the layout of the dialogue, the very UI itself, is completely different… Assuming there weren’t any more entries (it looks like the complete list to me) you only have one connection that is, in fact, connected when you took that screenshot. So the t:slim (“tslim” 
is using some variant of BLE; it only connects when necessary. Something is connecting to the Dexcom (DXCMR5).
If you are not confident with uninstalling the Dexcom app I don’t think there is a lot you can do to get further other than Tandem support; it is apparently their bug because it is the Tandem app which is failing to connect to the pump.
You could check to see if you can do a small manual bolus, 0.01IU or whatever their minimum is, next time this happens. If you can’t do a manual bolus (a meal bolus for 1g for example) that’s a 100% certain major support issue; it is different to what @jim26 originally reported because that was a dropped connection rather than an inability to establish a “new” connection.
One fact that I find amusing; my Omnipod does not appear in my bluetooth list anywhere obvious, unless it’s one of the “available devices” which I think are mostly my fire alarms.
@jbowler I don’t use the Dexcom app. The DXCMR5 is my G7 sensor which is paired to my pump via the TSlim app. I am also paired to the sensor via XDrip (2 channels). I use the Tandem app approximately 40% of the time to administer boluses, the balance of the time I do it manually. I mainly log everything in XDrip, which uploads to Nightscout and Tidepool for myself and my Endo who has 24/7 access via her own specific logins.
Oooh. Read “xDrip+” for “Dexcom” in my previous posts; they both use slot 2, even if you have “engineering mode” turned on in xDrip+ and say to use a different slot.
If you do have engineering mode turned on turn it off.
xDrip+ becomes very aggressive when a connection is dropped, this is somewhat documented.
That said, did you just intend to state that, while the t:slim app is reporting a “lost pump connection” (see the screenshot in the original post) you can, nevertheless, initiate a bolus from the app?
Good idea!! Thanks!
Thank you for the suggestion. I did give it a try, but didn’t notice much of a difference. From what I can tell, anytime the phone disconnects from the pump, it will not reconnect. For me that happens quite a bit since I don’t drag the phone with me all over the house.
@jbowler XDrip does get aggressive when attempting to make an initial BT connection , especially if it is the second in line (I paired my pump first). I have found that making sure any extra sensors (new or old) are not anywhere nearby helps in the XDrip pairing process, and I ALWAYS delete the previous BT sensor connection from my phone before trying to pair a new sensor. I have had fairly reliable success pairing sensors this way.
Agreed
That was a bug and it was fixed maybe a year ago. They never acknowledged either that it was a bug or that it was fixed but I have a black-box existence proof; before the change I could never connect xDrip+ second (after the Dexcom receiver), after the change it has always worked with a delay similar to that of the receiver. The second connection is slower because the G7 (and possibly G6) only broadcast every 5 minutes after the first connection has been set up correctly.
The bug is not related to this problem except that if you still see it (unable or very slow second connection from xDrip+) xDrip+ is going bonkers trying to connect to the new sensor or, maybe, reconnect after a dropped connection. That may saturate the ability of the 'phone to handle other incoming bluetooth connection requests. It certainly placed a lot of unnecessary load on the bluetooth stuff.
Make sure your xDrip+ is no more than about 6 months out of date if you still see the problem.
