You should not need to reboot the asus all the time.
Probably you have another problem that is causing some trouble.
Do you have a swap file created?
Can post the output of 'free'?
If you find that your internet is slowing down, then the most likely reason is that you didn't limit the upload speed.
Limit the upload speed (in transmission) to around 75% (or less) of your maximum upload capacity.

