I noticed this when the county fair came to town a mile away from my property because of the network load. The signal on my cell camera dropped when it was going on but as soon as it was over and there weren't 1,000+ people on their phones right down the road the signal strength went back up to full coverage.
About a year ago, on a Sunday, my Cuddeback stopped sending pics. I checked the signal with my phone, and it was 2-3 bars like always, and I could call or text from the same location as the camera. Cuddeback replaced the camera twice to no avail. I took one of the new ones into town, where it worked fine. The only thing that I can surmise is that AT&T(Hell be upon them) degraded the signal or the band width on the local tower for unknown reasons. I just bought a directional antenna to try, but I have little confidence that it's going to work.