New setup - sensors going offline

I just setup a Qolsys Panel 2+ and 8 mini Qolsys door/window sensors. I finished the setup yesterday afternoon. A few hours after arming the system, 3 of the sensors went offline. Everything is in a railroad layout apartment, typical apartment building construction. Two of them that are next to each other went offline almost the exact same time. These two are the two furthest away from the panel, and down a hallway, with some walls in-between, but are maybe 20 feet away from the panel. There is a third sensor in the room with the two that went offline, it is maybe 3 feet closer to the panel, and didn’t go offline. Then hours later a third sensor ( one room away from the panel) in a different room, went offline, but came back on its own later on.

I bought the Panel off e-bay as used/open box. It seems to be functioning properly, did all the self-testing the panel can do and passed. I had one sensor setup a few days ago on it and had no problems with that single sensor.

The 7 sensors that I installed yesterday are all new in box, but several years old. Meaning I bought them over 3 years ago, but the tabs for the batteries were still in and I pulled the tabs yesterday.

I am not at the location currently to physically check the sensors yet.

It seems too coincidental that the two furthest away from the panel, right next to each other, even if only 20 feet away, with a couple of walls in-between from the panel, went offline at the same exact time, right? But like I said, there is a third sensor in the room with the two that went offline, and is still online. And the third one is literally 15 feet away with on wall in-between the sensor and the panel.

Any thoughts? Bad sensors? Bad Panel? Too much distance/walls in-between sensors and panels?

p.s. Sorry for so much info/rambling… lol

The sensor antenna on the IQ Panel 2 is the thin white flexible antenna. It must be routed out the back of the panel and into the wall for proper reception.

Given the description it is likely that this antenna is inside the panel or pinched in the back plate. I would check that first.

Everything looks ok with the antenna… Still getting random offline and back onlines… :frowning: The panel is not being moved around and the sensors are not being moved either…

I had one sensor setup a few days ago on it and had no problems with that single sensor.

Which sensor was this and has it ever experienced an issue since? If that sensor has never experienced an offline issue, move it to a location where sensors have. Does the offline issue follow the sensor?

One thing I would try is a full power cycle of the system, then test sensors for functionality. To do so:

  • Disarm the System
  • Navigate to Settings > Advanced Settings > Power Down
  • Once off, Unplug the Power Supply from the wall
  • Open the panel and disconnect the internal battery
  • Leave the panel completely off for at least 2 minutes
  • Feel free to take a clear picture of panel internals and send it to us for review. Can send it via Private Message or email at
  • After 2 minutes minimum, plug in the battery and power supply. Turn the panel on via side button.

About 5 minutes after boot up, test sensors for functionality and observe to see if the condition returns or not.