Unfortunately what you're missing is the EP-R8 is a router, not a switch. If you want a switch you needed the S16 instead. The R8 is designed to support a different IP network on each interface, with none of them being on the same switch domain. Which is why it won't let you put the same network on more than one port - that's what routers are supposed to do. If that's not making sense to you then you really need the S16 instead...
JIm
