I have a dozen tags around my house. My iPhone sees some of them most of the time, and some are really hard to connect to.
First of all, I find some of the tag use examples on Ruuvi.com a little optimistic. I put one tag in my car, to see when it is warm enough. The garage, a wooden shed 50 m from the house, was not reachable from a window with line of sight to the garage. I put another tag on the porch, 5 m from the kitchen window. It connects, occasionally. I wonder if cold weather makes a difference for the tag on the porch. Now it is -5…+5 degrees, and the tag has the standard battery. A third tag, in my wine cellar in the basement, also connects only occasionally, but that I can understand, with reinforced concrete structures.
Any ideas, does cold weather affect the battery and then the output power? Or is there a good transmit orientation for the tag, e.g., perpendicular to its face?