I have this router/controller that's acting very flaky, show up for a second on my Omada cloud console, but then if I click to open it, it says "Controller disconnected". It's been doing that for days

Hi, I have a site with a local controller and three EAP660 that I have set up on April 18th (about 2 weeks ago). Everything was working fine, but then yesterday at 16:00, one of the three APs dropped