Conflict between RFM95W/LMIC and DS18B20 temperature

End Devices (Nodes)
7

You should not use pin 10 (default Slave Select) as in INPUT (even if you define another slave select pin). You can use it as an universal OUTPUT, but then you have to assign it as output before initializing the SPI bus, according to comments in SPI.cpp

void SPIClass::begin() {
  // Set direction register for SCK and MOSI pin.
  // MISO pin automatically overrides to INPUT.
  // When the SS pin is set as OUTPUT, it can be used as
  // a general purpose output port (it doesn't influence
  // SPI operations).

  pinMode(SCK, OUTPUT);
  pinMode(MOSI, OUTPUT);
  pinMode(SS, OUTPUT);
  
  digitalWrite(SCK, LOW);
  digitalWrite(MOSI, LOW);
  digitalWrite(SS, HIGH);

  // Warning: if the SS pin ever becomes a LOW INPUT then SPI 
  // automatically switches to Slave, so the data direction of 
  // the SS pin MUST be kept as OUTPUT.