The Free On-line Dictionary of Computing (30 December 2018):

Windows for Workgroups 3.1

    (WFW 3.1) The lesser known first release of
   Windows for Workgroups.  WFW 3.1 bundled an earlier
   386-protected mode networking stack with Windows 3.1.
   It did not support TCP/IP.

   WFW 3.1 was upgraded to Windows for Workgroups 3.11.

   (2018-08-15)