When rebooting a Windows 10 system that had ICS enabled, the settings would be lost. Clients that were using the shared connection could no longer access it even though it still showed enabled. The workaround was to disable and re-enable the checkbox button for: Allow other network users to connect through this computer’s Internet connection.
The long term solution involves 2 changes, taken from the below article:
- Modify the service titled Internet Connection Sharing (ICS) using the Control Panel -> Services. Change Startup Type to Automatic.
- In the following registry location, create a DWORD titled EnableRebootPersistConnection and set a value of 1:
After the above changes, configure ICS into a working condition (if necessary toggle the checkbox) and then reboot the system.