Internet dosn't work when connecting hdmi / usb hub I have bought a brand new MacBook Pro 15' and when I am connecting my screens, the wifi is still connected but the internet doesn't work.
when I am disconnecting the HDMI, the internet comes back.
I read that this is a known problem, but I didn't get any solution...

What should I do?
Try this, go to system preferences then network preferences. Select Thunderbolt Ethernet and "make service inactive" (click sprocket icon at the bottom)

This improved my WiFi connection speed.  My thought being that Thunderbolt is a multipurpose port also used for ethernet and may be taking priority when it is plugged into any device.  If you are using WiFi Thunderbolt ethernet is obviously not needed.