Only been a broadband customer with three for one week. Previously on copper through Vodafone max at 45mbps.
Not far from a recently upgraded mast (about 200m) getting about 350mbps on 5G phones.
After installation speeds next to router are running at approx 250mbps. So far the signal seems stable and the difference in up/down speed is very welcome. The ZTE MC801A router is a sturdy piece of kit.
However I have encountered one major flaw which support were unable to help with or believe that the problem should even exist.
Trying to use any streaming services (prime, iPlayer, YouTube ) is not possible on devices such as nvidia shield, firestick or smart tv, some will kick into action with a vpn turned on (not prime with my vpn). In addition we couldn’t access gaming servers or web based email ( we are both nhs staff).
from the main forum I found some information what suggested changing apn setting to ipv4 instead of ipv4/6 as it default on the router. Then all of the above issues resolved. Without the fix I would have cancelled. Three support refused to believe this was the issue.