@Adnan008 – so have had a chat with ASUS and they are not aware of any issues with high memory usage with the latest beta firmwares.
There is no plan currently to release any new beta’s firmware’s as ASUS feel the firmware’s are working well (relatively)
Maybe send ASUS a feedback form so they can study the configs and then Maybe worth going back to a previous firmware version as rebooting router every 4 days is not good 
In a completely sane world, madness is the only freedom (J.G.Ballard).
You need to login in order to vote