It's possible the APs are missing some check-ins with the HiveManager (what we call echo packets), but not enough to cause a full disconnection. If you could enable the following debugs on an AP with this issue, wait for the issue to happen again, and then pull tech data, we can check for missed echos to confirm this theory. The tech data will include a lot of information, so if we don't see any missed echos, I can check for other things as well.
CAPWAP debugs:
_debug capwap info
_debug capwap basic
_debug capwap stat
These will be erased if the AP reboots. You can also manually disable these at any time by adding "no" to the start of the command; for example "no _debug capwap info".
To get tech data in HiveManager, we will want to go to Tools> Utilities> Get tech data> Check the box next to the device> Get tech data (blue button at the top of the page this time). Please email this file to communityhelp@aerohive.com for review.
This guide reviews how to get tech data from the CLI of the AP in case that is more convenient:
https://thehivecommunity.aerohive.com/s/article/Collecting-Tech-Data-via-CLI
