Think of the media converters as a converter of the transport path of your internet. So you can put this media converter there and then connect it with Ethernet cable (what you call LAN) upstairs, and then either connect directly or connect to a router upstairs. Pay attention to the SFP module which must be plugged into this media converter, alone it will not accept fibre. The SFP module must match your fibre, and be aware of the maximum broadband of this media converter, if you have 10Gbps via fibre, but after converting you can only have 1Gbps, again it is not optimal. Have fun and greetings