Zigbee2Mqtt hangs regulary

Hi, I run HA with HAOS on a Raspi 4, 4GB with a fast 64GB SD card and recently switched from the dresden zigbee stick and deconz to zigbee2mqtt and the sonoff Stick (the new short one). I have about 45 Zigbee devices of many brands including valves etc. and everything runs like clockwork. For scheduling and changing font parameters in the frontend I installed HACS and some components.

The Raspi is in a passive cooling aluminium case that directly cools the chips. So a thermal issue is not very likely, as the case is just a bit warm. Also I use the original Raspi AC adapter.

Every 48 to 96 hours zigbee2mqtt stops working although its still running. All Zigbee devices are offline then. I only have to restart zigbee2mqtt and everything quickly gets online again. WLAN connected devices are not affected.

I don’t exacly know when this first appeared as sometimes the complete HA ist unreaponsive for abfew minutes and “comes back”, what I believe is a network issue (duckdns).

I did not find similar issues here, ran all updates in the last 6 months.

To solve this I would like to write an automation that regulary checks responsiveness of one zigbee device and restarts the zigbee2mqtt process. Can anybody help me with that?