Please paste the interface config from router and the switch.
This could be a physical layer problem, like bad cable or wrong cable used for the interface connectivity. Try changing the cable between the switch port and the router interface. Check whether it is a cross-over cable. It should be a straight cable between the router and the switchport.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...