I recommend that you phone contact your regional D-Link support office and ask for help and information regarding this. Refer to this thread and that web site link and inform them that the file listed doesn't work.
We find that phone contact has better immediate results over using email.
Let us know how it goes please.
Thank you for your reply but the latest firmware for my model was not found on this site.
Error 404
http://dlinkmea.com/partner/media/product_item_downloadables/GAN9_ET235B_B_DL_DSL2750U_R5B027_ME_EN_2T2R_with_DWM_157_D1_57df7ff0e78cc.RAR