Had the same problem random disconnects, drove me crazy tried all sorts, in the end I found it was the Freezer, on same mains ring, every time it turned on or off it browned the board out, put it on a different mains ring and all is good, I did until I solved the problem use a inline home made UPS , but i just used an inverter off a car battery on a permanent digital charger. to run the machine, can buy a pre made one on amazon from about £50 upwards depending on the power demand, as it being supplied through a constantly charged battery via an inverter, its isolated form any spikes, in the house main power rings.
When the Freezer was causing the issue the compressor would kill the connection when it turned off and on as well as the extractor fan, now all seems to be ok with the freezer on a different loop.
There is a UPs here for £40
the wattage should be plenty for the Ortur.
Induction motors like compressors, have a high demand on start up, and this causes a lot of boards to brown out. for a millisecond.