configure the network on the Windows computer (the one with RStudio) - at least open the port in the firewall; check this using another computer/laptop on the local network using a web browser (a.b.c.d:8787, where a.b.c.d is your local IP address).
configure router - your laptop should have fixed IP addresses so set up DHCP and then set up port forwarding.
SSH is a nice idea (much more secure) but a bit more complicated.
Regards!