you could try ad blocking this way....
http://www.snbforums.com/threads/adblocking-with-combined-hosts-file.15309/
I use this and the experimental ad blocker in the latest merlin firmware
Thanks Merlin for the 378.50 firmware..
installed 378.50_ta-dpi firmware on my AC56U.. all seems fine, Wireless, Traffic Analyzer works just fine, as well as AiProtection.
RT-AC56U (OC 1000,533)
Bootloader v1.0.2.3
378.50_ta-dpi