Hi. I'm pretty sure there was some similar reports about this before, although I searched the forums and was unable to find the thread. We have an ongoing annoyance with cnMaestro, where it reports various ePMP Raidos as being offline, when they really are online just fine.
Yesterday for example, it reported one of our AP's offline, yet the 17 SM's connected to that sector were all online just fine. And (of course) the AP was online fine too - it was passing data to the SM's, we could log into the AP, the uptime on the AP was 24 days, and it came back 'online' according to cnMaestro without us doing anything about 10 minutes later.
Our other monitoring software (like WhatsUpGold) doesn't report the AP's as being down when this happens - just cnMaestro. If the radios reported incorrectly as down are SM's, then when we log into them, we find that the 'session time' are the long... so it's not a real de-register situation.
So, I'm not sure if I can give many clues to track this down - this seems to be rather random, no real pattern to which AP's or SM's are reported as offline when they aren't that we see. It's also not a major issue - it's more of any annoyance - except that we kinda have to check when we notice a red dot on the map to see if it's really down or not really down at that time.
V3.1 will likely be out in the next week or so, so I can wait till then to upgrade everything and try to track down a pattern. Right now, most of the networkis 3.0.1 with some 3.1-RC30's spread around.