between 2AM and 6AM internet would start dropping packets like crazy

about 20 years ago I was remotely troubleshooting a microwave connectivity problem that occurred at a clients workplace about 10pm each night. Lasted about an hour. There was no one at work then but data transfers between their server and the mothership would fail.

One night the client went to the site at night to check an alarm and noticed there was a bobtail truck parked next to the building. The aero deflector attachment on its roof blocked line-of-sight with the tower, causing the problem. He asked the driver to nap at some other location in the parking lot and the problem went away.