If your connection issue occurs when you move between a mobile data connection and a wifi connection or vice versa, and is particularly affecting Android apps (although it often affects native apps as well, for me it is mainly email synchronisation issues to to connection problems) then it is a very well known and widely reported bug in Sailfish that has been present in 4.3 and many earlier releases. There is no fix available but various workarounds do work - these vary from rebooting the phone to using Sailfish utilities in Settings to restart the network sub-system. There are other command line workarounds as well, if you’re into that type of thing - which I’m sure others will jump in and advise on - but I believe they all still just restart the network sub- system to get the connection back. Its a huge frustration for many who get this bug, but in the absence of a fix from Jolla there’s not much else we can do.