Its strange but disabling SecureDNS solved the browsing prob.
From yesterday, yet dont have browsing prob.

May be previously I disabled SecureDNS 10 mins only so after 10 mins prob was back.

From yesterday I have disabled SecureDNS permanently & no browsing probs yet.
Boot prob too seems improving with each passing day.

If any query will post here.

But have to disable SecureDNS & thats bad.

And one point, when I keep SecureDNS enabled, I have noticed that sometimes GUI shows something like SecureDNS cannot connect to this network & after few secs everything fine. I have noticed this quite a few times.