I have 3BB, using the router they supplied, and both 2.4 and 5 WiFi signals reach at least 30 metres around my home. I do have an Xaomi AC1200 booster to get a better 5Ghz signal to my Fire TV stick in my bedroom through several walls. Get 3BB to come out and re-set the router first, or you can do it yourself via 192.168.1.1 and put the user name & password shown on the bottom of the router.