
Devices work as advertised, they split the ethernet port into two separate cables as four wires are not typically used for 100 megabit connections. If you need a gigabit connection, you're out of luck as it uses all eight wires. In that case, you'd be better off getting two inexpensive managed switches that support VLANs and configuring them to isolate your networks.

Wi-Fi adapter D-link DWA-140, black
46 Review

High Gain Wireless Network Adapter - TP-Link Nano USB Wifi Dongle with 150Mbps Speed for PC Desktops and Laptops. Compatible with Win10/8.1/8/7/XP Linux 2.6.18-4.4.3, Mac OS 10.9-10.15 (TL-WN722N)
46 Review

π ASUS USB-BT400 USB Bluetooth Dongle Receiver - Compatible with Laptops and PCs, Plug and Play for Windows 10/8/7/XP. Supports Printers, Phones, Headsets, Speakers, Keyboards, and Controllers in Black.
79 Review

TP Link TL WN823N 300Mbps Wireless Adaptor
55 Review

π Juiced Systems Silver BizHUB USB-C Multiport Gigabit HDMI Hub with 3 USB 3.0 Ports, Gigabit Ethernet, 4K HDMI, SD/Micro SD, and USB-C Power Delivery
11 Review

π uni USB C Hub with Ethernet Adapter, 4K HDMI, Gigabit Ethernet, and 3 USB 3.0 Ports for MacBook Pro, iPad Pro, XPS
11 Review

HB-UMLS Sabrent USB 2.0 Hub with 4 Ports and LED Power Switches for Each Port
12 Review

π CERRXIAN RS232 to Ethernet Serial Device Server - TCP/IP Converter with 1Port DB9 RS232 Serial to Ethernet Connectivity
3 Review