On a SonicWALL TZ105, I have a LAN with the IP address of 172.16.20.1 & netmask of 255.255.255.0. I defined a VLAN with the IP address of 172.16.21.1 & a netmask of 255.255.255.0. Both are on physical port X0.
I already have many PCs on the LAN pointing to gateway 172.16.20.1, but when I tried to add a PC to the VLAN pointing to gateway 172.16.21.1, it doesn't work. I can't even ping 172.16.21.1 from the VLAN PC and it can't access anything.
All the PCs are on the same managed switch (D-Link DES-3028) which supports VLANs. I even defined ports that connect to the SonicWALL and the VLAN PC as VLAN trunks, but the VLAN simply doesn't work.
How does one debug VLAN problems? I am simply hitting a brick wall here.