DNS Filtering and DNS Resolution

Hello,

We recently enabled DNS filtering through our SonicWALL on our internal network, and it's been working well overall. However, we're seeing an intermittent issue where users are occasionally unable to resolve DNS. In most cases, refreshing the page 3–4 times resolves it without any further intervention.

For context, our SonicWALL's DNS Server 1 and 2 are configured as 156.154.54.200 and 156.154.55.200. Internal devices are pointed to the SonicWALL's interface as their sole DNS server, with no secondary configured. Our support rep confirmed this is the recommended setup.

Has anyone else run into this? If so, what ended up resolving it?