I have 2 dell switches a slightly older 3348 and a newer 3448 which I have configured a separate vlan on both switches for one port only that will be connected to a dmz port on our router. (The router and the computer we need to use on the dmz are in different buildings.) When connected directly to the DMZ port of the router, it properly gives out a dhcp address (testing with my laptop) and is pingable which is how I know its working. But when I do the same through the vlans it doesn't work.
The setup is
Laptop -> Dell 3348 (port 44) -> Dell3448 -> (port44) -> DMZ
which doesn't work
Laptop -> DMZ
All other computers and devices are on VLAN 5 (none are on the default of 1) and these two ports are on VLAN 10 on both switches and are in "T" mode which should be trunking.
The other options on the port are "U" and "F".