@RemcoCopp 

A wired unit reporting as 'isolated' usually means its heartbeat is no longer reaching the controller...and this is the direct result of loss of communication, which can be ethernet, or simply a power glitch somewhere causing the unit to reboot.  Given that your ISP modem also seems to be dropping out, I would take a long hard look at both your power situation and also the unit and/or wiring that connects the ISP modem and the AP that are dropping out.

With more detail...like are your APs powered by POE, via your switch or injectors....we can probably offer more detailed advice.  

As a simple test, move the 245 that Isolates daily to the same room as the switch and connect via a short cable...does it continue to isolate daily?

If you have access to a UPS, try powering all your equipment (modem, router, controller, switch, AP/injectors) from the UPS and see if the modem stops disconnecting and the rest of the system stabilizes.