Can you open the unit’s IP in your browser to see what the internal webserver puts out? It is possible the high voltage inverter is failing to produce 380V, resulting in a reboot. Then it goes for DHCP lease again (~12sec) and so on.
In every case when I power it up it functions correctly with proper voltage, however after a few minutes it then drops. Should I proceed with the test you outlined?
I do have a multimeter but am fairly unskilled at electronics.