E1200 - Can't Upgrade firmware

Hi guys,

I'm suffering the pains of a slow wireless connection. If I run a test connected directly to my modem, I get the 50mbps I pay every month. If I run the same test via wireless, only 14-18mbps tops.

I have changed channels, modes, tweaked QoS... tried every single tutorial out there. Can't do.

My last resort is upgrading the firmware, but I can't either, since every single time I try, my router reboots automatically at 4%. Tried several browsers, no luck. 

Any ideas?

Thanks very much.