Orbi AC3000 + Comcast 400Mbps -- Router reports 487Mbps Cannot get more than 220 Mbps via LAN

So, I have a couple suggestions, if you're still working on this. I saw your differential results between ISP > modem > computer compared to ISP > modem > Orbi > laptop.

I propose unplugging the Orbi satellite(s), which will ensure you're connected directly to the Orbi router.

Also, have you been conducting this test wirelessly, or over ethernet cable? Try both ways to see if one or the other is the issue. When you're running the test directly connected to the modem, you MUST be using ethernet. When you're running the test on the computer by way of the Orbi, which are you using (wifi or ethernet)? If you've been testing over wifi, which version network card does your laptop have? E.g., 802.11g, n, ac? And how many data streams does it support? 2x2? 3x3? Are you connected via 2.4GHz or 5GHz? I'm just wondering, since when you test directly from the modem, you use ethernet, and maybe when you're testing via the Orbi you're using wifi, if the discrepancy can be explained by a limitation on your laptop's wireless networking card, which band you're using, etc. 

What does it say on the QoS page in the Orbi settings? Did you run that before? If so, maybe it's possible the Orbi is limiting you based on your old connection speeds, and you need to either factory reset the Orbi to clear that, or run it again so it updates with your current bandwidth.