If you have to take turns to use the internet you may have already thought about wireless internet sharing, which lets 2 or more computers and laptops use the same internet connection. But there is actually another easy way to do the same thing.
It may sound a little strange but you can use your electrical wiring, specifically the power sockets, to connect to another computer and hence use the same internet connection. The electrical current uses a different frequency so it won’t interfere with the internet connection.
The advantage it has over wireless internet is that you literally just plug in the equipment, there is no signal problems or security key numbers to bother with.
So what do you need? Assuming you already have broadband you just need two plugin devices to start with (each consists of an adaptor that plugs into the socket and an ethernet cable, which looks like a telephone cable, that connects the adaptor to the modem or to the extra computer you want to connect.)
If you want to give this a try, make sure you choose a mains network starter pack that says “85Mbps” as the cheaper ones will not give you a fast connection. Remember that you need to put the adaptors onto the same ‘ring’ so that they are connected. For example your upstairs power sockets might not be on the same ring as the downstairs ones.
Also, make sure the 2nd computer or laptop you want to connect is network ready (ie has somewhere for the ethernet cable to plug into, such as a network card or LAN card. Most modern laptops and computers will already have this, but if not you can buy them very cheaply).