I have a Realtek WLAN controller which uses the rtl8723be driver on the
3.16.7-21-desktop kernel.  After connecting to a wireless network, the
connection works for about 20 or 30 minutes.  The connection then drops, and
nothing short of rebooting can get it to connect again.

Examining /var/log/wpa_supplicant.log shows that the disconnection always
happens after a group rekeying:

wlp2s0: WPA: Group rekeying completed with 5c:d9:98:e4:d9:d0 [GTK=TKIP]
wlp2s0: WPA: Group rekeying completed with 5c:d9:98:e4:d9:d0 [GTK=TKIP]
wlp2s0: WPA: Group rekeying completed with 5c:d9:98:e4:d9:d0 [GTK=TKIP]
wlp2s0: WPA: Group rekeying completed with 5c:d9:98:e4:d9:d0 [GTK=TKIP]
wlp2s0: CTRL-EVENT-DISCONNECTED bssid=5c:d9:98:e4:d9:d0 reason=2
wlp2s0: CTRL-EVENT-REGDOM-CHANGE init=DRIVER type=WORLD
wlp2s0: CTRL-EVENT-SCAN-STARTED 
wlp2s0: SME: Trying to authenticate with 5c:d9:98:e4:d9:d0 (SSID='FrettchenNet'
freq=2462 MHz)
wlp2s0: CTRL-EVENT-SCAN-STARTED 
wlp2s0: SME: Trying to authenticate with 5c:d9:98:e4:d9:d0 (SSID='FrettchenNet'
freq=2462 MHz)
wlp2s0: CTRL-EVENT-SCAN-STARTED 
wlp2s0: SME: Trying to authenticate with 5c:d9:98:e4:d9:d0 (SSID='FrettchenNet'
freq=2462 MHz)
wlp2s0: CTRL-EVENT-SSID-TEMP-DISABLED id=0 ssid="FrettchenNet" auth_failures=1
duration=10 reason=CONN_FAILED

This looks to be the upstream bug report:
https://github.com/lwfinger/rtlwifi_new/issues/22