[ubuntu] wifi not working time to time ubuntu 16.04 BCM43142

Hi,
I have installed ubuntu 16.04 in my hp af103ax laptop which has broadcom BCM43142 wlan. Now I have installed latest 6.30.223.271 through synaptic. Also
I have set the security in router to wpa2/aes instead of tkip. But still time to time the wifi is not working. Network manager is showing the wifi is coected but inteet
is not working , ping to gateway is getting destination host unreachable. But in the same laptop with win 10 it is working perfectly.

wlo1 IEEE 802.11abg ESSID:"souradeep"
Mode:Managed Frequency:2.412 GHz Access Point: B8:C1:A2:1D7:5C
Bit Rate=72 Mb/s Tx-Power=200 dBm
Retry short limit:7 RTS thrff Fragment thrff
Power Management off
Link Quality=36/70 Signal level=-74 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
I have dmesg but not showing any such errors.

Please help me here, what I should do to fix it properly.