hello,
i contact the d-link support , and they send me a link to upgrade my dsr-250 with a new firmware ....coming from ....d-link taiwan ..
http://dtrack.dlink.com.tw/temp/case/DEUR20151209000001/2/1/DSR-250N_A1_FW1.09B76_WW(1210084600).09b76_ww
they told me it will have to fix the problem...
furthermore : this firmware is WW : World Wide , so compatible with the whole world !!
note : the firmware is for REV : A1