If you're measuring speed on a wireless device, then speeds in the range 140-550 sounds normal due to the 802.11ac technology the Hub 4 uses. Speed will vary with the device itself, the band it connects on, and fall off with distance, through walls etc. You'd be unlikely to see faster than 600 Mbps over wifi with a Hub 4 even if all possible circumstances are optimal.
You'd need premium Wifi 6 devices and a Wifi 6 router/mesh system to see speeds approaching 1 Gbps (assuming that there's no cable connection problem underling), and VM currently don't have a Wifi 6 capable hub that operates at 1 Gbps, although work continues to address that.
EDIT: The only reliable way of testing your broadband speed is to use a device connected by an ethernet cable, but if you're seeing similar low speeds you need to try the following: Connect to the hub by clicking on this link http://192.168.0.1/ That should 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.