Hello Naofumi,
We compiled the sample code you gave us but got an error of too few argumemts in function call when compiling Main.C in Line 182: HAL_Lowpowermode(); After commenting this line out and compiling we were able to test it against our windows sample app and managed to transfer data for about 3 hrs without any issues. We also ran several smaller tests sending data for about 20-30 minutes and the data was transferred without issues. We'll do some more testing on this but can you tell us about the remote device setup(the device that you are connecting to?).
Best Regards,
Stonestreet One.