I upgraded my NAS with a 5G USB based ethernet NIC. When connected to the CRS305, SwOS reports the link as 10G, while the NAS reports its link as 5G. Shouldn't the CRS305 be reporting 5G?
Also, I am only getting about 500Mbits of throughput. If I connect the NAS to a 1Gbit switch, I get the full 900 Mbits. So, even though there is a link, something is off.
My CRS309 running RouterOS reports 5Gbs:
This with a QNAP USB3 5G adapter on the other end. I assume you connect the same adapter to the gigabit switch? If not, are you sure your NAS has USB3 ports?