Hi,
Im hoping someone can help!! My WiFi router developed a fault and i returned it to a sender and reverted to using a old router i had (ASUS RT-N56UB1) as i am looking to save some money i probably wont be looking to change this router at the moment.
Currently i am on firmware v 3.0.0.4.378_7220 and have beeing trying to upgrade, so went to Asus own home page and found RT-N56U downloaded the firmeware but i keep getting this error

The only differance i can find is that this does not have the "B1" at the end of the model, i have looked a few places but i can not find firmware for a RT-N56UB1 im hoping someone can help.
If not i will have to revert to another old router i have which is a Netgear D6000.