I have set 8.8.8.8 and 4.4.4.4 as primary and secondary DNS servers for DHCP in my router. It seems they do not get propagated over to the pi (after reset it still has the old 8.8.8.8 and 1.1.1.1) in both Nameservers and Nameservers.Configuration. I tried this with both dnsproxy=yes and dnsproxy=no in /etc/connman.prefs.
So the config is persistently the one from /etc/resolvconf/resolv.conf.d/head which gets prepended to /etc/resolv.conf and which I have set in previous posts.
I assume that resolvconf is being called by OpenVPN, so that needs to be switched off for now. Because you had already added tethering and OpenVPN to the configuration, it’s proving a bit more complicated to revert to a simpler set up.
As I see it, the DNS IP addresses should come from one of three possible sources: (1) the router via DHCP; or (2) statically set via connmanctl config; or (3) statically set via My OSMC (2 and 3 might effectively be the same). Until /etc/resolv.conf is picking up the correct nameservers, I don’t see how we can move forward.
Have you disabled OpenVPN?
A solution has already been discussed: you manually set the DNS addresses on your phone. All the complication after that point has been about getting DHCP to work. If you can live with a manual setting, then everything else works.
Here are some apps for android to change dns in your phone:
And for iPhone:
I do not need an app to change the DNS which should be set automatically by OSMC, sorry. Worst case: I set them up myself to use i.e. 8.8.8.8.