OpenVPN server has hard coded DNS - how to change this to allow OpenVPN to use local DNS
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 188.8.131.52 which bypasses Pihole. There are no settings in web interface on OpenVPN page that I can find to change this. I cannot find any other ways to change this. Typically OpenVPN server configuration file can be edited to change any settings but I cannot access this file on ER605.
How can I change the hard coded DNS for OpenVPN server on ER605?