Qolsys Window Sensor Goes offline frequently

Have Qolsys IQ Panel 2. Probably have 16 sensors around a single story, 1800 SF home. Using IQ Mini Door/Window Sensors. Most sensors are fine, But i have 2 that are now frequently going offline. Have replaced batteries, deleted them from panel, rebooted panel, added them back into the panel, even put in new sensors. They are still going offline. One is about 40 feet from the ATT High Speed dual band router with 1 wall between it and panel, and the second is 60 feet from the Panel with 2 walls in between. Do i need a wifi extender? Please let me know if you need additional info to troubleshoot.
One other question, do sensors need to be a certain distance away from other sensors or other magnets? I ask because i put the sensors on the windows, and 2 magnets on the frame outside the window. This is to allow me to open windows and still keep the window alarmed.
Many thanks.

They are still going offline. One is about 40 feet from the ATT High Speed dual band router with 1 wall between it and panel, and the second is 60 feet from the Panel with 2 walls in between. Do i need a wifi extender? Please let me know if you need additional info to troubleshoot.

The alarm sensors do not use wifi. Your wifi network has no impact on them. They use a 319.5 mhz rf radio directly communicating with the panel.

One common issue that pops up when using the IQ Panel 2 is that the sensor receiver antenna is a thin white flexible antenna which must be routed out the back of the panel into the wall for best communication. While in the manual, this is often missed, and if left inside the panel it can affect sensor reception.

Double check this to be sure your antenna is routed out the back of the panel into the wall.

One other question, do sensors need to be a certain distance away from other sensors or other magnets? I ask because i put the sensors on the windows, and 2 magnets on the frame outside the window. This is to allow me to open windows and still keep the window alarmed.

See the info page below for a description how to do this and what to avoid.

Yep. The antenna, though not very long, was partially obstructed. Once the obstruction was gone, all the sensors have stayed online. Thank you for the quick response! We appreciate you!

Is there a way to add on to the antenna, to make it longer? I recently replaced all the batteries in all the sensors. Two again frequently lose communication with the panel. Thank you.

There is no way to lengthen the IQ Panel 2 sensor antenna. As long as it is routed out of the back of the panel properly into the wall you should be good, but distance or attenuation can impact signaling.

Is it always the same couple sensors showing offline? Are they the most distant or is there metal very close?

I am not seeing any offline sensors at this time. Can you confirm the names of the two sensors you are referencing?