Hi, I don't understand what kind of freezes we are talking about, thousands of RUT240s are running on the RUT2_R_00.07.01.2 firmware without problems. You can try using the RUT2_R_00.07.00.0 firmware and the modbus package for the RUT2_R_00.07.01.2 firmware. But in this case, no one can guarantee the stable performance of the device.
Best regards.