On my home network my wifi router provides DHCP and DNS services. When any pc boots up, it gets an IP address from the router and its name is registered. I can then use NSLOOKUP by either IP or PC name and find all of the machines on my network. I do have a desktop that is wired to the router, but it too uses DHCP.
Some routers may not register local names. Some users like to use Google's 8.8.8.8 DNS servers which can't resolve local IPs/names. In that case you can enable network discovery.
This is kind of a long thread, but it shows troubleshooting steps that you can do to analyze your network.
You can run the Powershell script on your pc's to enable network discovery.
I log on to my machines with my Microsoft account. That allows me to authenticate to any other pc and see the shared folders. Before I used a MS account, I defined a local user with the same name and password on every machine.
I do not recommend using the guest account. I feel that it exposes my files to any machine that might happen to find a way on to my network.