First you need to turn on Sharing in windows (
ONLY DO this is for a Network set to PRIVATE) on BOTH
NOTE: I avoid
sharing apps that allow skirting the Routers protections that are left on.
My routers Firewall log shows even attempts to get a my Content server (no port forward set hole) several times a month. These are pros, that found my (WAN) IP via posts (probably linked to Calibre topics) and tried
.
Microsoft has tips on setting up sharing (use official sites only for security issues unless you are a GURU level)