Try and create a dummy VLAN 999 with Subnet 192.168.255.0/24 and MX IP 192.168.255.1. Then set that dummy VLAN 999 as Native on ports 2, 3 and 4.  Then make sure that all inter-switch links (links between switches) are trunk, with native vlan 999, and all VLANs are allowed on the trunk. ... View more