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Hi -- I'm quite new to this forum but I've followed some threads here.

I want to set up VLAN but don't know exactly what hardware/configuration I need.

My plan is this:

VLAN A -- ground floor
VLAN B -- first floor
VLAN C -- other building/garage
VLAN D -- server

what I want/need to set up is that every VLAN (A,B,C) should be able to communicate with D since there is a Mail and File Server.
but A,B and C should bot be able to communicate with each other.

I have already purchased an ER5120 -- guess that router should be able to take all my purposes.

But my question now is if a smart switch is enough or do I have to upgrade to a managed switch?

And how is it possible to prevent some VLAN from communicating with each other? I've found a good tutorial on TP Link site
( https://www.tp-link.com/us/faq-887.html) but the problem here is that all can communicate with each other.

Would be nice If you could give me a specific switch-model that should work (16 ports should be enough I guess)

Thank you very much in advance!