I took the static ip thing for the alexa Bridge to mean it needs a static internal ip address, ie your dchp server needs to dish out the same ip address to your phone/Tablet. This may be why it stopped when the other chap changed his router, alexa was thinking the alexa Bridge was elsewhere.
I found that waking up my phone & rm tasker app once an hour has been enough to make any issues dissapear, without making the phone drain of power so quickly,so the phone can still sleep but still work. The developer may have fixed the issue now, but I wouldn't know as it's been working fine either way.