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#11
Just a drive by suggestion, often these days we do not rely on the free security supplied with windows although the One supplied with Windows 10 is very capable.
Do you have any third party security suite on any of the systems, these would normally contain a firewall, that, unlike the windows firewall may be set to block the ports used for windows networking.
If you are using 3rd party security confirm that the network ports are open or use the user guide and open them .
The full list of ports is available here List of TCP and UDP port numbers - Wikipedia but it's better to check the manual for any firewall software as they will have more specific lists and maybe a one click open button