Lan with wired and wifi PCs used to work, now only the wi fi ones work and wired can't even ping each other

I have a weird problem that's been driving me crazy for some weeks. The basics: I have four PCs in my home LAN. The four of them are on the same workgroup, homegroup is disabled, I use the old style networking. I have users with same name and password on all the computers, the shared folders have the permissions and security settings properly configured to allow the users to access, and everything worked until some weeks ago. The four computers had internet, sharing folders and printers, remote desktop or VNC, even games ran fine in local multiplayer lan mode. (Like Quake 2 using TCP IP or DOO

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