Can you access the Windows 7 machines from a Windows 10 machine?
I suspect you're experiencing the networking bug introduced by a recent Windows Update (see https://www.askwoody.com/2019/january-patches-for-win7-kb-4480970-and-kb-4480960-break-networking/)
Microsoft created a fix but you have to download it manually. See https://support.microsoft.com/en-us/help/4487345/update-for-windows-7-sp1-and-windows-server-2008-r2