Do you have the Hub in modem mode and connected to the Orbi which is set to DHCP. Or are you using "access" or "bridge" mode on the Orbi.
Speeds being limited to <100 might be due to a "bad" ethernet cable connection between them. Change to a new Cat6a cable and see if it improves.
Test as Iotharmat say too
-------------------- John --------------------
I do not work for VM. My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired 2 WiFi,) SH2 in modem mode with Airport Extreme Router +2 Airport Express's. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.
Could be a wifi issue, but the Orbis are decent kit and should work well, so without presuming too much it may still be worth checking out your hub's status data. Pull up the log in page for the hub. But don't log in, just click on the link "Check router status" That'll bring up a window with five tabs. Open the Downstream tab. Select all the text (Ctrl-A if using a keyboard), copy it (Ctrl-C), then paste it (Ctrl-V) into a reply here as TEXT not screenshots. Post that, do the same for the Upstream and Network log. You'll get an error message when you post the Network log, just click on "post" a second time. Then we can check for any obvious problems with power, noise or error counts.