Openvpn – How to push the own DNS server to OpenVPN

I have defined an unbound DNS server on my VPS and it appears to work. I need to use the DNS server instead of public DNS servers because some ISPs have blocked public DNS IPs. My openvpn.conf file is:

    dev tun
    proto tcp

    # Notice: here I set the listening port to be 80 to avoid possible port blockage
    port 80

    ca /etc/openvpn/easy-rsa/2.0/keys/ca.crt
    cert /etc/openvpn/easy-rsa/2.0/keys/server.crt
    key /etc/openvpn/easy-rsa/2.0/keys/server.key
    dh /etc/openvpn/easy-rsa/2.0/keys/dh1024.pem

    user nobody
    group nogroup
    server 10.8.0.0 255.255.255.0

    persist-key
    persist-tun

    #status openvpn-status.log
    #verb 3
    client-to-client

    push "redirect-gateway def1"

    #pushing public DNS IPs

    push "dhcp-option DNS 208.67.222.222"
    push "dhcp-option DNS 208.67.222.220"

    comp-lzo

As it is suggested here, I tried to use my server's IPs (say 11.22.33.44). So instead of

    push "dhcp-option DNS 208.67.222.222"
    push "dhcp-option DNS 208.67.222.220"

I just put

push "dhcp-option DNS 11.22.33.44"

In openvpn.conf above. However, after restarting openvpn, I see that my client can still connect to the OpenVPN server but no pages can be rendered anymore.

What can be wrong here? How can I solve this problem?