OpenWrt can create multiple Lan interfaces, and set different network segments for each Lan interface. Between different network segments, as long as the LAN firewalls are the same, they can access and ping each other. Assigning them to different LAN firewalls will not communicate with each other. The following is an example picture of assigning different fire strengths:
If you only want LAN10 to be able to access LAN20, and LAN20 cannot access LAN10, you can set the following settings in the openwrt firewall area
If you can't ping and access according to the above setting method, then you need to close your Windows firewall or reset the firewall inbound rules, because the Windows firewall only allows access to this network segment by default (Under Win10, others are not clear).
Reset the settings related to file sharing and Ping echo, and it will be fine.