In my experience, OEM replacement antennas are hard to come by. They looked good from the outside and the price was attractive. It's clearly lacking in quality compared to the originals, but I can't quite figure out what's different. The antenna cable inside rattles compared to the original, and they appear to be a bit cheaper. However, I have found that they got the job done, so the antenna cable itself can meet the requirement, but the case cannot. However, for what they are, they may suit your needs.
π StarTech.com NETRS2321P: 1-Port RS232 to Ethernet IP Converter, Serial over IP Device Server - Black
5 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
π USR-TCP232-410s: RS232/RS485 Serial to Ethernet Adapter/IP Device Server with DHCP/DNS Support
4 Review
π StarTech.com NETRS232 Serial to IP Ethernet Device Server - DIN Rail Mountable - Serial Device Server - Serial Over IP Device Server (Black)
4 Review