I have a simple home network, wired and wireless. All devices connected to the network through my ASUS router. I used Linux Mint 20.3 on my Linux machines. I can ping all the computers on the network, and I can also ping the router. There are no switches between any of the devices.
DID YOU CHECK TO SEE IF MAC FILTERING IS ENABLED ON YOUR NETWORK SOMEWHERE
TRY USING A LAN CABLE TO SETUP THE SHARE, EITHER DIRECTLY FROM YOUR HOST PC OR THE BACK OF THE ROUTER, IF THAT WORKS THEN YOU KNOW ITS A WIFI EQP OR PROTOCOL ISSUE