We were using a DNS VS listening on port 53 but configured to handle TCP protocol as shown here: ltm virtual /Common/VS_DNS { destination /Common/10.10.10.10:53 ip-protocol tcp mask 255.255.255.255 pool /Common/pool_dns profiles { /Common/tcp { } } source 0.0.0.0/0 source-address-translation { pool /Common/SNAT-10.10.10.10 type snat … “F5 TMM Crash”