Hehe, easy after all:
You’ve forgotten to prefix the DevAdr with 0x to denote hexadecimal. Now the code thinks 26021622 is just a decimal value, which in hexadecimal happens to be 0x018D0EF6. So, you’ll need to use:
static const u4_t DEVADDR = 0x26021622;
Lessons learned: use the right terminology and show some code…