http://docwiki.embarcadero.com/RADStudio/Tokyo/en/Installing_Socket_Components
The socket components are not installed by default. To use the socket components, you must install the dclsockets<.bpl> package.
To install the socket components:
C:\Program Files (x86)\Embarcadero\Studio\19.0\bin
.Note: These steps are one-time installation instructions. The socket components should be available for all future projects.
Delphi xe 10.2之安装 TServerSocket 和TClientSocket
原文:https://www.cnblogs.com/jijm123/p/14266340.html