DNS QUAD9 not working?

Hi,

I have disable use peer DNS on DHCP client. I have set 9.9.9.9 as DNS and even in DHCP server dns to 9.9.9.9 but when I check this adress: https://on.quad9.net/ it says that Im not using DNS quad9. Where could be a problem?

Tnx

Your ISP could be intercepting any DNS requests not destined for their servers and redirecting them.