Windows 10 upgrade Wifi drops after few seconds

Hi

I have dell latitude E6330. I recently upgraded the same to windows 10. After that I am having this very frustrating problem.

My wifi runs for few seconds and than even when the wifi connection shows full signal strength, I am not able to connect to anything on internet.

After which when I switch off and switch on the wifi back on my laptop, I again have internet for few seconds/minutes. Sometimes it last for few minutes sometime its stops in few seconds. I haven't been able to find any specific time pattern on this.

I have brodcom 802.11 network adapter. and windows 10 OS. I checked the dell support and I have ran multiple diagnostics  and I have all the updated drivers(atleast per dell diagnostics)

Can anyone please help. this is my work machine and it drops VPN everytime and need to reconnect. This is very frustrating to say the least.