VenuSQ Disconnects from Phone after multiple makeWebRequest calls

I have a watch app which has been working very well for several years (https://github.com/OpenSeizureDetector/Garmin_SD/tree/master/WatchApp/source).

It collects 5 seconds worth of accelerometer data and a heart rate measurement, then transfers it to an Android phone app that is running a local web server using makeWebRequest() (https://github.com/OpenSeizureDetector/Garmin_SD/blob/master/WatchApp/source/GarminSDComms.mc#L49)

Recently users with VenuSQ devices have reported that after a watch firmware update they have an issue that after several hours of running, the watch disconnects from the phone (Garmin Connect shows the watch as disconnected).   The only way we have found to reconnect the watch is  to re-boot it.   I have a VenuSQ device and am seeing the same issue using Garmin Connect V4.71 and the VenuSQ firmware V4.90.

I suspect that this may be to do with multiple makeWebRequest calls happening simultaneously if for example  the data transfer is slow or the web server responds slowly, so I have tried making a different version of my app where I can tell it to transfer less data.   It seems to run for longer, but the fault still happened after about 10 hours when I tested it.

The same app code is working ok on a ForeRunner 245 - I have only had reports from users about the VenuSQ devices.   

My bug tracker issue for the problem is here:  https://github.com/OpenSeizureDetector/Garmin_SD/blob/master/WatchApp/source/GarminSDComms.mc#L49

So I think a recent watch firmware for the VenuSQ must have changed something.    I do not know how to obtain an old version of the watch firmware and install it so I can test to see if this is true or not - but if someone can give me some guidance I will do it.

Please let me know if you need any other information or would like me to try a different watch firmware.