Orbi AC3000 & Xfinity 1gb Service??

I have 1G service (though not xfinity) and it works for me when hardwired.  There is *some* speed degradation when going through the router (vs direct connect to Internet, as in right into the optical terminal) but that should be expected on a device like this.  It has it's own processing / nat / etc to do and you will not get true 1G service when going through it. 

Also the speed tests inside the orbi are worthless in this case because you cannot select the test server.  So you need to do the tests from the computer, just FYI.  Also make sure you select a server that is with your own ISP and is local, to get more accurate results.