Configure for 1 or 2 for SSIDs supporting smart devices. Configure for up to 10 in industrial environments with applicable client devices.
DTIM stands for a Delivery traffic indication map or message. It is basically an additional message added after the normal beacon broadcast by your router or access point.
The more often that DTIM is transmitted, the more often that your mobile devices wake up, and the more battery that it uses (due to the lack of “sleep”). By setting a low value of DTIM and beacon interval, you can effectively keep your devices awake indefinitely so they never go into sleep mode when idling. In some cases, the “no sleep” setup can use up to 10~20% additional power consumption.