We have been having the exact same issue since upgrading to 28.5. We get down alerts for random AP's across all of our networks. Most of our networks share the same ISP connection and are behind a Palo Alto firewall. One of our networks is a remote site that has a completely different ISP, is behind an MX250 and connected to an MS390, and we receive random down alerts for the AP's at that location too but not for the MX or MS. We've had 2 separate tickets open with no resolution, they want us to call as soon as it happens so they can collect more information while it's happening.
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