So it seems that the the culprit may in fact be RF interference from the wifi AP, although if the sensor itself isn’t using WiFi or RF signals at all, why would RF affect it so drastically? Are there any other hardwired sensors that work well in high-interference areas that I could consider? I’m also concerned that if a hardwired sensor is having this much trouble, how much more trouble would a wireless system have in the same environment?
I wouldn’t expect this on a wired sensor, and I can’t really answer that question as to why or which model would be better.
I’ve had a similar report from a Google access point which seemingly interfered with a Z-wave device very close by. Even though the radios are not using similar frequency, the proximity seemed to cause the issue. But that is a case of RF saturation seemingly affecting signaling. In this case you are saying it appears to be affecting the sensing element itself.
What wifi access point is this? What is the model number? Does it run especially hot? Does it have an integrated fan?
I wouldn’t expect and would be a little perplexed by RF directly affecting the sensing element of a wired motion.
Can the access point be repositioned away from the detector as a test? Try adding a little distance and see if the same issue occurs.