What does a router do?
A router forwards IP packets between networks using its routing table, mainly corresponding to OSI layer 3. NAT, DHCP, Wi-Fi and firewalling are optional functions, not requirements for routing. Home gateways commonly combine them in one device.
What does a switch do?
A layer-2 switch forwards Ethernet frames within a network using learned MAC addresses. Broadcasts and unknown unicast destinations may be sent to multiple ports within the appropriate VLAN domain. A switch does not necessarily reserve an exclusive connection or replace general security controls.
VLANs, layer 3 and hubs
VLANs divide a physical switching network into logical networks. Communication between them requires routing, for example through a router or layer-3 switch. A hub repeats signals to its other ports; this is not technically the same as creating broadcast frames. Hubs have little role in modern Ethernet networks.
Troubleshooting in practice
Check link, VLAN membership, local address, prefix, gateway and DNS separately. An incorrect gateway can prevent external access while local connections still work. Our public tests run from the server in Düsseldorf and do not diagnose your private switch ports. Local tests and device logs complement the results.