MX Linux can't browse web 'can not open page'

Odd problem last night.  I'm on my MX Linux (Debian) machine browsing the web then suddenly it says 'can not open page'.  Wifi is still connected.  I can ping 1.1.1.1 but not google.com (unknown host).

Disconnect / reconnect, no luck.  Disable wifi entirely & reconnect, no luck.  Reboot and it works again.  Then ~10 min later same problem.  Browsing fine then suddenly cant load pages.  

I check the wifi config and all the DNS settings are still there.  After a while I checked /etc/resolv.conf and all it had was the loopback not my DNS config :

nameserver ::1
nameserver 127.0.0.1

So I edit resolv.conf as root and added this to the top then everything worked again for the rest of the night.

nameserver 9.9.9.9
nameserver 2620:fe::fe