my home sharing button sudenly disappeared from second computer?

Hello rolandfromexeter,

I'm sorry to hear you are having these issues with iTunes on your new computer. If you are having issues setting up or connecting to Home Sharing, you may find the information and troubleshooting steps outlined in the following articles helpful:

Use Home Sharing to share iTunes content with other devices on your home network - Apple Support

Get help with Home Sharing - Apple Support

Sincerely,

- Brendan

I had the same problem today with my new macbook. Homesharing is still there but somehow is turned off in the update. On mac and pc go to preferences under file for pc and under iTunes on mac. Then click sharing preferences on both computers and check share library on local network. This fixed my problem and took three advisors to figure it out. Hope this helps!