Is it true that you can use a router and route between subnets on a lan when all the pc's and the router are connected to only one switch?
Well.. you can use the design that you have set up currently but its not a scalable design. The more number of vlans , the more interfaces you need on router. The scalable and the recommended design is to have a trunk between the router and switch and create sub-interfaces for inter-vlan routing between the vlans.
Please see the link below for the same: