I have just bought a Three PAYG SIM to test the signal strength in my area prior to trying 4G Broadband and I have to say I am very disappointed both with the signal AND the Three Coverage/Status pages.
After installing the SIM in my iPhone Xs, I got intermittent 4G (zero to 1 bar) indoors, falling back to 3G when performing a speed test and even poor 4G outdoors ranging from 2 bars to zero and falling back to 3G.
Speed tests to TBB reported 2.0/0.5 indoors when they worked at all and 2.5/1.8 outdoors IF it stayed on 4G then entire time. One 3G test did report better at 8.0/1/5 but then it found a bit of 4G and that took over and the speed dropped. No single 4G test ever beat 2.5/1.8, even away from buildings.
Now here is the good bit... I went indoors and looked at the Network Status page and it said this...
"We're really sorry. There's an issue with the network in your area at the moment. We've checked the coverage in this area. Have a look at the map below for details. It looks like you could supercharge your coverage in this area using Wi-Fi Calling. Check out our Wi-Fi Calling page to find out more. Use coverage checker to see the typical signal strength in this area. This information is updated every 30 minutes. (last update 1:15 pm 15 August 2019)"
OK, I filed that away for when I rang Three support.
When looking at the Coverage Checker for my postcode, if I omitted the device name it reported pretty poor coverage (which was the main reason I wanted to test the SIM first before committing to 4G Broadband) but if I put the correct device in (iPhone Xs) it suddenly painted the entire map and said "Excellent. You're all set; you're in a 4G Super-Voice area and your phone is compatible, so you'll soon notice your signal smashing through indoor blackspots."
Hah! Fat chance!
So I rang Three support (Asian call centre of course) and was told there was no fault in my area. I quoted the website "We're really sorry. There's an issue with the network in your area at the moment." and was told there was no fault, merely poor reception on my phone, maybe I would like to try to make a call standing outside?
I then quoted "Excellent. You're all set; you're in a 4G Super-Voice area and your phone is compatible" and was told that the coverage checker was merely an estimate of what was likely.
If you want to see what their estimate is like, go to http://www.three.co.uk/Discover/Network/Coverage and enter Coylton as the town name and pick iPhone Xs from the phone type dropdown. Apparently despite it looking like the page has been given a fresh coat of red paint, all that means is 2.5Mbps outside and 2.0Mbps indoors.
Is there ANY point in me persevering and trying a Category 6 modem with 8dB Omni antenna? It is a lot of cash to lay down when the best they can offer is 2.5Mbps, imaginary faults and made-up coverage checkers. It looks like my 4.8/0.9 landline is going to be staying at this rate!