Wow, this was a simple fix but it took me entire day to find it. Issue is not that ER605 has hardcoded 8.8.8.8 for DNS and it is overwriting the client config settings. Issue was that Android phone...

I am trying to use Pihole for ad blocking while connected over OpenVPN to ER605. Problem is (after much testing and reading online) that OpenVPN server on ER605 has a hard coded DNS pointing to...