Routing DNS through L2TP Tunnel (xl2tpd)

Dear PavelGL.

Thank you for the kind assistance. I applied the settings as advised by you. However, I intermittenly get remote DNS, most of the times I have Cloudflare DNS servers which is quite problematic for my application.

video of the steps applied here

Remote DNS alternates now between:

172.70.113.84	    CLOUDFLARENET	US
108.162.218.13		CLOUDFLARENET	US
172.70.109.88		CLOUDFLARENET	US
172.70.113.122		CLOUDFLARENET	US
172.70.113.38		CLOUDFLARENET	US
108.162.218.45		CLOUDFLARENET	US
108.162.218.14		CLOUDFLARENET	US
172.70.109.41		CLOUDFLARENET	US
172.70.113.12		CLOUDFLARENET	US
172.70.229.81		CLOUDFLARENET	US
172.70.229.41		CLOUDFLARENET	US

or

2001:4888:801c:ff00:168:d::                   WIRELESSDATANETWORK	US
141.207.243.254 254.sub-141-207-243.myvzw.com WIRELESSDATANETWORK	US

Is there a way to filter out CloudDNS servers and keep the real remote ISP DNS servers only?

Any input would be greatly appreciated.

PS. A gentleman had suggested to have this rule at this post:

15000:  from all iif lo lookup vpn

However, I cannot figure out how to add this rule.

Thank you so much.