Pathlights shows offline then online then offline

Hello,I have several pathlights that operate between 2 groups. In each group, I have a few lights that report as being offline, then will go online 30 minutes to 1 hour later, then offline 30 minutes to 1 hour later. I have several that are doing this, but not all. I have power cycled the bridge and the problem persists. I have not yet changed the batteries in any of my lights as I only installed them 3 months ago, plus the lights show the batteries to be full. Any thoughts? Thank you.