cisco 1242 dtim wmm

Choosing “Mixed 802.11g, 802.11b and 802.11n” and using WMM function are forbidden
for wireless mode.

When client devices receive a beacon that contains a DTIM, they normally wake up to check for pending packets. Longer intervals between DTIMs let clients sleep longer and preserve power. Conversely, shorter DTIM periods reduce the delay in receiving packets but use more battery power because clients wake up more often.

The default beacon rate is 2, which means that every other beacon contains a DTIM. Enter a beacon rate between 1 and 100.

https://www.cisco.com/c/en/us/td/docs/wireless/access_point/12-3_7_JA/configuration/guide/i1237sc/s37ssid.html

WMM is in QoS , 

QoS is disabled by default (however, the radio interface always honors tagged 802.1P packets even when you have not configured a QoS policy). This section describes how to configure QoS on your access point. It contains this configuration information:

https://www.cisco.com/c/en/us/td/docs/wireless/access_point/12-4_3g_JA/configuration/guide/ios1243gjaconfigguide/s43qos.html