For devices configured to use Umbrella for DoH and DoT: An issue has been reported where Umbrella may close the connection for devices sending multiple DoH/DoT requests over a single TCP connection. While only some DoH/DoT client implementations are ...

Ran across this edge-case when trying to deploy BlueCat + Cisco Umbrella integration. This bug does modify the ARCOUNT, but more importantly, it modifies it without updating the UDP checksum. Packets are rejected as soon as they arrive at a DNS serve...