A controller, comprising: a processing resource; and a memory resource storing machine-readable instructions to cause the processing resource to: cache a router advertisement from a router of a plurality of routers associated with a virtual local area network, VLAN, of the controller; select, in response to a client device associating with the controller, the cached RA from the router; unicast the RA from the router to the client device, characterised in that the machine-readable instructions further cause the processing resource to: send router solicitations to the plurality of routers of the VLAN of the controller; unicast, to the client device, a zero lifetime RA in response to the router of the plurality of routers failing to respond to the router solicitation in a predetermined threshold time to cause the client device to disconnect from the router; and unicast, to the client device associated with the router of the plurality of routers, a different RA associated with a different router of the plurality of routers to cause the client device to connect to the different router. a processing resource; and a memory resource storing machine-readable instructions to cause the processing resource to: cache a router advertisement from a router of a plurality of routers associated with a virtual local area network, VLAN, of the controller; select, in response to a client device associating with the controller, the cached RA from the router; unicast the RA from the router to the client device, characterised in that the machine-readable instructions further cause the processing resource to: send router solicitations to the plurality of routers of the VLAN of the controller; unicast, to the client device, a zero lifetime RA in response to the router of the plurality of routers failing to respond to the router solicitation in a predetermined threshold time to cause the client device to disconnect from the router; and unicast, to the client device associated with the router of the plurality of routers, a different RA associated with a different router of the plurality of routers to cause the client device to connect to the different router. cache a router advertisement from a router of a plurality of routers associated with a virtual local area network, VLAN, of the controller; select, in response to a client device associating with the controller, the cached RA from the router; unicast the RA from the router to the client device, characterised in that the machine-readable instructions further cause the processing resource to: send router solicitations to the plurality of routers of the VLAN of the controller; unicast, to the client device, a zero lifetime RA in response to the router of the plurality of routers failing to respond to the router solicitation in a predetermined threshold time to cause the client device to disconnect from the router; and unicast, to the client device associated with the router of the plurality of routers, a different RA associated with a different router of the plurality of routers to cause the client device to connect to the different router. send router solicitations to the plurality of routers of the VLAN of the controller; unicast, to the client device, a zero lifetime RA in response to the router of the plurality of routers failing to respond to the router solicitation in a predetermined threshold time to cause the client device to disconnect from the router; and unicast, to the client device associated with the router of the plurality of routers, a different RA associated with a different router of the plurality of routers to cause the client device to connect to the different router.