Hi, I am new to Mikrotik and this is my first post. I have been using a rb4011 and love it and I just upgraded to a rb5009. I have my modem connected to port 1, 2.5G, and for some reason I can only get 200Mbps download speed. When I switch the wan port to port 2 I was able to get in the 900sMbps. I tried with default config and clearing the default config and on OS version 7.05 and 7.1.1 and got same results. I also tried it on two different rb5009 same symptoms. What settings am I missing to get the port 1, 2.5g port to do higher speeds? My main interest is my isp is offering 1.8Gbps now.

Check the Advertise-Speeds on the Interface
Make sure 2.5G is advertise....
For diagnostic purposes maybe only advertise 2.5G and remove everything else.