Haven’t had any problems with temperatures personally, but my box is on the E/NE side with at least a little shade.
Anything else going on from 2-5pm that might be messing with signals? Other WiFi operations in the home, are you cooking a lot with a microwave at that time? What exactly do you mean by “shuts off?” You’ve lost connection and can’t see your data? Does the data ever catch up? (like later in the evening, has it filled in?)
What you might need instead is an access point closer to your Sense device if it’s too far from your router, etc. A fair number of users have run into this problem.