Did you make sure you are sending the radius attribute noted in the config guide? Multi-Domain With multi-domain authentication, one device can be authenticated on each of the data and voice VLANs; if a second device is detected on one of the VLANs, the device will not be granted access. In this mode, Hybrid Authentication is used and Voice VLAN authentication is required. This mode is recommended for switchports connected to a phone with a device behind the phone. Authentication is independent on each VLAN and will not affect the forwarding state of each other. Cisco Meraki switches require the following attribute pairs within the Access-Accept frame to put devices on the voice VLAN: Cisco-AVPair device-traffic-class=voice
... View more