My switch have internet, but no clients have internet?

You probably need to set all client ports to user ether1 as master port. Check in Winbox ⇢ Interfaces ⇢ Ethernet ... the column Master port should show ether1 for all client ports, or all ports should be part of a bridge. From terminal, you can view the master port for all ports with:

Other signs is: Before logging in with Winbox, the neighbours tab shows IP 0.0.0.0 even though the switch has an IP. This will occur, when you are cabled to a switch through a port, that is not connected to the switch chip or cpu.