1. You cannot be on both, ethernet and WiFi at the same time. When you are trying to connect to both, the fastest network wins.
2. Have you configured WiFi correctly on both, computers and printer? Can you see the WiFi router? Also check Device Manager and make sure that WiFi driver is "in".
3. Test WiFi router with mobile or similar device, chances are that router is not configured correctly.
You are given too few info to give direct help. Perhaps better platform for questions like this one is forum answers.microsoft.com.
HTH
Milos