I suggest that you login to your router to determine what network (and IP address) is being assigned to the hub by DHCP. It will only use the network that you configured it to use, and will not randomly change networks. You imply that you don't know which Wi-Fi network it is connected to. I Why do you suspect it is related to a Wi-Fi issue? The red light can indicate several things LINK.
Other than an occasional red light, are you experiencing any actual problem with the operation of the hub? I have multiple Wi-Fi networks to choose from and it may be connected to a weak Wi-Fi signal. I'm finding that my Harmony hub intermittently shows a red status light almost every day.