Wish it talked about the cursed adapter. Would you have two of these adapters on each end, and the single cable would be split into two separate pairs for 100 Mbps ea?
The reviews of them are full of negative comments from people who don’t understand what they are, and think they’ll split one network cable into two, like a three-port switch - even though most of the listings are quite clear that you need to connect two ports at each end of the connection.
Most of the listings are, though, quite evasive about the fact that, even used correctly, they’ll not provide throughput over 100Mbps.
That one even sells them in pairs, but it certainly doesn't help that actual 3-port switches are also available in a similar form factor.
It's an ugly hack, but hey, there's a lot uglier in active use.