iMac AC2200

Hello,

I replaced my Apple Extreme Base station in my home with an AC2200 Orbi Micro Router (RBR20) and although it is working fine to connect my home iMac to the internet, I am no longer able to access the hard drive on this iMac from the outside. I have used the Orbi app to set up Port Forwarding to the public IP address of the router and am using 549 and 548 as the external and internal ports, respectively. These are the settings that worked on the Apple Extreme base station, but these settings do not work now. Advice welcome.