Yes, it is a cheaply built wooden house, as is typical in Southern California, from the 70s. The backside of the house is directly at the back alley, where the trash bins and through traffic are (see [1] for an example). The NAS is maybe 4m away from the trash bins.
I have the same problem, but it is not a problem for my Seagate X16s, that have been going strong for years.