Why am I having network issues? 3 computers, all Windows 10, one computer can see everyone else but others can't see that one computer

Three computers on a network, all on Windows 10. They were initially networked using HomeGroup when that setup existed long ago, and I mention that because maybe the creation of network using that method could be the cause of the current problem. All on same router, one with Ethernet, the other two use Wi-Fi. They were initially setup where everything was working fine, file sharing was functional, USB printer that is on the ethernet computer shared to other comps. Currently the shared folders on the two computers on Wi-Fi can be seen by the ethernet comp. The Wi-Fi computers can see each other

Question by MebBunny on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.