I'm assuming before going for the nuclear option, you've exhausted all wi-fi connectivity options? I only say this as I've got hive and it's absolutely rock solid. I previously had nest and that had problems but the fix was changing a router setting which stopped it kicking idle stuff off the network.
I'd even be tempted to change the wireless part of your router before changing heating system by using a mesh system added to the router and disabling it's internal wi-fi.