I haven't changed any wireless settings in the laptop and I never had a problem with my old router. I was trying to see if it is only happening after the laptop wakes from sleep but it doesn't seem to be the case. Would the latest Merlin build possibly help?Do you get the same range with the 5300 you got with the N-16 ?
Are you sure that the settings on laptop and desktop are not set for computer to control wireless ? If not set to always on the OS could be turning off connection after no activity for x minutes