This kind of problem occurs in very rare case. It can be caused due to inactivity of some services which are necessary for running Internet Connection Sharing(ICS) so make sure that all services of ICS are enabled. Following services should work properly in order to use ICS.
Application Layer Gateway Service
Network Location Awareness (NLA)
Plug And Play
Remote Access Auto Connection Manager
Remote Access Connection Manager
Remote Procedure Call (RPC)
To check or enable these services, follow the below given steps:
Open “Run” command by simply pressing “Windows key +R” and type “services.msc” and hit “Enter” key.
To enable any specific service, double click on the entry of service on right Pane window.Make sure that its “Startup Type” is set to Automatic.