Could be a few things, the speedtest.net server being used is similar to the above, however you can change this so check it's one of the closest to you. The other thing could be that the cable connecting the R3 to the modem is limited, in which case try swapping out the cable, even if it is the one we provided and check again. Test over ethernet if you can ideally.
Otherwise for WiFi try this:
Split the WiFi bands, give 2.4/5GHz different names and apply - you'll want to connect to 5GHz specifically for speeds
Use a WiFi analyzer to find the least congested channel and change to that
Experiment with the widths to see what gives better results
Ensure it's in an elevated position - not on a metal surface
Ensure there aren't any electrical / wireless devices e.g headphones etc within close proximity ~3 feet if possible
Set the antennae to this position _ | | _
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