Adblock + mullvad VPN

I have a "TP-Link Archer A7 v5" Router using OpenWRT Firmware obviously...
The VPN I choose to use was "mullvad" VPN and I am aware of Wireguard and adblockers on that and whatnot (that is my next thing to test) but I am using their OpenVPN not WireGuard

I want to use any adblocker on the router, I have both Installed "simple adblock" and "adblock"
It does not seem to work with the VPN Running. To my research I may have to modify my ".ovpn" config File or my DNS as it may be routing all traffic through the Mullvad VPN DNS their for "adblock" wont work?

I want the VPN to Run as well as the Adblocker to work at the same time, I get the concept of using an extension in the browser and or even WireGuard but would it be possible to make "Mullvad" VPN (OpenVPN) work with Adblocker on the Router? I essentially want all connected devices either via Ethernet or Wireless to be Routed through the VPN at the Same time get ads blocked from the Ad Blocker installed onto OpenWRT.

This was the guide I used to make Mullvad work (if it helps)

I can show my configs if needed or any "/etc" file I also did try messing with the Settings , with "Forced Zones" etc but after testing a site I been trying to block for testing purposes ( it always seems to load. Their was a few Times having a Wire Connection and Constantly "Refreshing" and "Restarting" adblock on the Router it seemed ? to block the site ? to say the least its not persistent .

Is their anything I can do or should modify to get both things working at once despite the other options such as WireGuard and just using an Browser Extension ?

I tried looking into my ".ovpn" config file I am not great when it comes to looking and creating or modifying open VPN Config Files.

This is the config file what follows after is what I assume is a PGP Key or Some Big Key

dev tun
resolv-retry infinite
verb 3
remote-cert-tls server
ping 10
ping-restart 60
sndbuf 524288
rcvbuf 524288
cipher AES-256-GCM
tls-cipher TLS-DHE-RSA-WITH-AES-256-GCM-SHA384
proto udp
auth-user-pass /etc/openvpn/mullvad_client.auth
reneg-sec 0
remote 1195 # ca-mtr-ovpn-002
remote 1195 # ca-van-ovpn-202
remote 1195 # ca-tor-ovpn-101
remote 1195 # ca-mtr-ovpn-001
remote 1195 # ca-tor-ovpn-102
remote 1195 # ca-van-ovpn-201
remote 1195 # ca-tor-ovpn-002

Your client .ovpn file does not have any route directives in it, therefore you're currently dependent on the push route directive from the server... which you do not control. Your preferred DNS server might not be reachable via the VPN.

With WireGuard you can make use of the AllowedIPs directive... which you do control.

You may have to reconsider your VPN configuration.