I keep losing bluetooth connection to my iPhone so the NF function is useless!

I set up a device (fan) to turn on whenever I am nearby. It works for a few minutes, but invariably I will come near it later and it asks me if I want to connect or it has lost bluetooth connection altogether. That makes this function completely worthless since the whole idea is for it to work and turn on the fan automatically whenever I approach. I might as well go back to reaching around an switching the fan on manually. Very disappointed with the product. No other bluetooth device I have has such an unstable connection to iPhone so don’t tell me it is my iPhone’s fault.