USB controller problem during higher heat inside of control box

Hello,
we are using balenaFins for an IOT project and have some issues with the network connection and the USB controller.

Description of environment:
The balenaFins are placed in control boxes (stainless steel) and are working as controller and logging units for sensors. In the control box there are as well power supplies and electrical wirings.
The balenaFin case has an open lid and is connected to a din rail mount. It is powered with a 24V power supply.

Os:

  • Raspbian (image form the balena website)

Hardware:

  • balenaFin version 1.1
  • RPi compute module 3+ lite

Connections:

  • 3 DI inputs for power supply status
  • 8 DO relay controls
  • 2x USB serial converters
  • 1x network interface

Problem description
During higher temperatures we are loosing the network connection to the device. At the moment we have no temp probe inside the control box, but when I checked yesterday the inside temperature of the cage, it was about 42°C (Outside temperature 29°C).

After I opened up the control box and it cooled down to the outside temperature, the balenaFin started to work again. Closing the control box caused again problems. Later in the evening, the balenaFin was running fine until the next late morning (09:58 am). Since then, it is not responding any more. The last reported temperature was 60°C.

Troubleshooting steps done
*Changed the balenaFin board and the compute module -> same results

I have saved the system logs form the balenaFin, it looks like the USB controller stopped working and devices get reattached.

Extra Info
We have also installed a “normal” RPi 3B+, for testing, it is working without any problems and shows up temperature above 66°C. It does the same function as the balenaFin and is located within the same control box.

Questions
Has anyone the same problems as we have?
Is there some recommendation for us to do?
Does anyone has as well problems with USB controller?

Thank all of you in advance for any kind of input.