Hi Steve,
Thank you for posting your query in Microsoft Community.
The network device you are using right now with Windows 7 may not be compatible with Windows 10. You can visit the computer manufacturer's support website and check for any updated driver available. There could be possibility that latest network driver may be available for Windows 8.1. If so, you can use the same driver in compatibility mode for previous version of Windows in Windows 10.
You may refer to: **Make older programs compatible with this version of Windows**
Also, you may refer to suggestions provided in the thread below which can help you fix issues pertaining to Windows 10 upgrade.
Howto: Troubleshoot common Setup and Stop Errors during Windows 10 Installation
Hope this information is helpful. Please feel free to reply in case you face any other issues with Windows in future.