@passta, is your management VLAN being issued IP addresses from the DHCP server on the MS390 stack, and is the the MS390 switch stack receiving its IP address from itself? If so, this might be causing the DNS mis-configuration error. There is this caveat regarding management IP addresses and Layer 3 addresses, “The management interface for a switch (stack) performing L3 routing cannot have a configured gateway of one of its own L3 interfaces”. You might need to reconfigure your network so the management VLAN has its Layer 3 interface on the MX.   Reference: https://documentation.meraki.com/MS/Layer_3_Switching/MS_Layer_3_Switching_and_Routing, Layer 3 Interface Caveats ... View more