Thank you @egor-tensin! I've been struggling with this problem for years. This is the first work around that actually works! I added that line under the [ipv4] section of my VPN connection file and then restarted the network manager with:
sudo systemctl restart NetworkManager.service
Now it's actually using the DNS specified by the VPN rather than just my default ISP's DNS.
Thank you @egor-tensin! I've been struggling with this problem for years. This is the first work around that actually works! I added that line under the [ipv4] section of my VPN connection file and then restarted the network manager with:
sudo systemctl restart NetworkManager. service
Now it's actually using the DNS specified by the VPN rather than just my default ISP's DNS.