No internet since my new monitor?

I've just connected a new Benq Zowie XL2546K monitor to my PC and everything works fine. Only I can't go on the internet. The Wi-Fi connection is recognized and the PC shows that there's internet, but as soon as I open Firefox or the internet explorer it says "Server not found" but the internet runs normally with the laptop. What did I do wrong? If it's the new monitor, help!

It will hardly be due to your monitor, after all, it does not affect your network connection. Perhaps you should check whether all cables are plugged into your router and whether your router is working?

All cables are plugged in and the internet works on other devices too.

Then maybe run the Windows network diagnosis? (if you have a PC with windows)