Hi Gordon and James – I have limited experience with BLE App development so the information provided is just in the interest of helping with the fault finding. I have come across 2 situations where intermittent connections are one of the symptoms – even if it is a single connection and then never again.
The first is battery power whether it is the Central (phone) or the Peripheral (Mooshimeter). From what you have described Gordon and the signal strength that the RSSI is reporting this is less likely.
The second case that I have experienced is where there is another device that uses the same Service UUID and the App missed one of the error checks to exclude this particular Service and Characteristic combination. The area of code that I had this issue with was the connect to peripheral and characteristic setting notification call (I can’t remember off the top of my head what the iOS method call is). The solution for me was to do a conditional logic of if/then/else and account for all conditions. I have only developed on iOS so I am taking a leap that a similar situation may occur on Android. Hope this helps and doesn’t confuse the issue.