Homegroup is one of those features that Microsoft never upgraded properly since the it was introduced to Windows. As a result, many users have been complaining that Homegroup breaks after upgrading to a new version of Windows 10.
According to Microsoft, this is a known issue, and while the isn't a permanent solution nor the company is details what is doing to fix the problem or the future of Homegroup, it's possible to use a workaround to prevent breaking Homegroup when upgrading to a new version of Windows 10, such as the Creators Update or Fall Creators Update.
The workaround is to keep one of the other computer in the Homegroup running and connected while you perform the Windows 10 upgrade, so that your device can contact that computer to download the Homegroup configurations after the installation.
If you've already went through the upgrade, and Homegroup seems not to be working anymore, the only way to fix this problem is simply recreate the Homegroup network.