1. I presume that NIC1 is on your LAN. Is this correct?
2. What device is 10.20.20.3? That one is confusing.
3. What is the default gateway for your DHCP clients? Is it 10.20.20.100?
4. If 10.20.20.100 is a DNS, why is it different for your clients? Your DNS server should normally forward to 184.108.40.206 and 220.127.116.11 (unless you don't want clients to access the server's DNS).
5. The DHCP router can't be 18.104.22.168 unless your clients are connected to that interface. Since they're not, the default gateway should be 10.20.20.100 (I still need to understand what 10.20.20.3 is).