Sensors failed from various hardware sources

homeassistant delivers a mystery to me. I have sensors from different hardware and homeassistant shut down this sensor and do record any data of them for a specific period of time. This happens not every day, but regulary.
First I thought my hardware was somehow exhausted and overloaded, but this seem not the case, as there is plenty of ram and processor capacity available.
I have no idea, where to look to track this down. My conclusion is, that there is a problem inside HA as different hardware units deliver the data. Above that I have the sun azimuth (data coming from the internet) and this show the same problem.
I you have any ideo, kindly let me know, thanks in advance Christian