Problem with ETH net.cfg

Hello,
I am trying to set the correct IP address on my Pixhawk 6X, but every time I reboot the device, the configuration file gets deleted. I was able to successfully perform this operation on other Pixhawk models, but I can’t get it to work correctly on this one. What could be causing this issue? I can share screenshots if needed.

make sure you have a microsd card inside the Pixhawk 6X, if you do, try formatting the card

After many tests…
Actually, the problem only occurs when my RFD900 UX radio module, which I use for telemetry, is connected. When it’s connected to the Ethernet port, I can’t modify the IP address—it reverts to the default 0.0.0.0. However, when it’s disconnected, everything works fine and I can see the IP address correctly changed to 192.168.20.5. This is really strange, especially since they operate on different frequencies.

my module RFD900 is connected to the uart4&i2c port.