I've owned the DSR-250 a couple of years now and have never upgraded the firmware.
Serial number is QBKI3G7000480
Firmware is 2.11_WW
HW version is A3
Picture is at:
https://cln.sh/biPFMgI tried updating with DSR-250_Ax_FW3.17_WW
I get the following error in a red box:
Firmware is NOT available to be installed in NON-Supported Hardware machine, please use correct firmware version for your devices.