You shouldn’t lose your connectivity just by switching from Single LAN to VLANs. The IP configuration of the MX as Single LAN gets copied across to VLAN 1. The only issue could be if the MX ports are not configured as Access Ports on VLAN 1 - this could be the case if there was a previous configuration on the MX. Make sure the ports are configured as Access, VLAN 1 and enabled, and you shouldn’t lose any connectivity. Once you’re at that starting point you can then move to creating the DMZ.   If all your ports are configured correctly and you’re still losing connectivity then I’d contact Support as it’s unlikely that you’ll get the assistance here that you need to troubleshoot this one. ... View more