FORTIGATE 7.6.1 DNS ISSUES

Hello members.

I recently upgraded firewalls from 7.2.10 to 7.6. I have 2 firewalls connected in fabric, the root fortigate at the headquarter connects directly to dns server and it is reacheable but it cannot reach the fortinet dns 96.45.45.45 or google public DNS 8.8.8.8.

The down stream fortigate accesses the internal DNS through a tunnel.Clients can reach the internal DNS however when you ping directly from the fortigate the ping fails. I have noticed on the DNS settings with default settings the fortinet dns 96.45.45.45 shows reacheable while the internal DNS shows unreacheable but if I change the source IP address of local out traffic, the internal DNS shows reacheable while the fortinet DNS 96.45.45.45 and google public DNS 8.8.8.8 shows are unreacheable