Router Ethernet (WAN (Modem/Internet) and LAN) ports have a link type of 10/100 Mbps and 10/100/1000 Mbps. Routers with 10/100 Mbps will not receive or distribute speeds higher than 100 Mbps, whereas routers with 10/100/1000 Mbps will receive/distribute speeds up to 1000 Mbps. You will see these specifications on the manufacturers box for any router.
We recommend that you confirm the Ethernet port specs instead of going off the AC1000+ specifications. Sometimes the AC wireless specification can be misleading and the router will only support 10/100 Mbps Ethernet link capacity.