First steps by using V-Lan

I do believe Vlan 1 is the default for most switches, some companies refer to it as the management Vlan, mine is a different brand then yours but I can’t even change Vlan one, and it starts at 2 for adding new ones.

Try anything other then Vlan 1, you will need to add a new Vlan table.
As far as DHCP goes if the Vlan on Blue is configured and working correctly then under Network then DHCP you can configure the options there for Blue DHCP also, it has to be a different network then Green.

Also Note if using Orange with or without Vlan there is no option to have DHCP on it from IPFire.