Any time you use your Iphone to check your speed you are obviously connected via WiFi and as third party speed testers you use are end to end , WiFi is part of that test ( and WiFi speeds are not guaranteed ).
The BT speed tester shows the speed ONT to Hub , and Hub to device, and is the only speed test that could be used to provide evidence of network problems…..as explained on another of your posts , you share bandwidth, so if you and other members of ‘PON’ are intensely downloading simultaneously ( including running speed tests ) the speed could dip below the minimum guarantee but the odd occurrence is immaterial, it’s would have to be consistently below the guarantee to warrant investigation.
The speed you posted although slightly below the guarantee at over 650Mb is still massively over what your usage requires, so cannot be the reason for your apparent issues.
Hi. My records, taken c/o the "My BT" app via my iPhone 12, indicate that the download speed has fallen below BT's minimum stay fast guarantee, almost every other day for the last two months. BT 's initial solution was to upgrade my package to Halo 3. However and although we live in a one bed bungalow, the issue appeared to get worse. Readings taken c/o "Fast.com" via my iPhone 12, indicate that the internal wi-fi speeds drop by up to 50%, with all three mini discs are attached. I'm simply trying to establish if the issue could be external, but I don't know how I as a customer, can measure the incoming speed to the ONT.
This neatly sums up my issue. That and the fact that I get conflicting advice from BT's visiting engineers, who mostly appear to be sub contracted these days? The only one I have seen who was directly employed by BT, identified an issue with the external overhead cabling and advised that if it persisted, to contact customer support. Having done so, the next engineer, who was a sub contractor, connected his laptop directly to the ONT and as it appeared to indicate a reading of exactly 1gb, he refused to investigate further.
When you're on FTTP the line speeds are fixed - between your ONT and the exchange data is transmitted at (approx) 2.4 Gbps downstream and 1.2 Gbps upstream; between the ONT and your hub, 1 Gbps. Your throughput end-to-end is dependent on a number of factors, including the package you've subscribed to, congestion on the local optical network (which you share with up to 31 other subscribers), congestion on the wider internet, and (if relevant) congestion and interference on the WiFi network.
Using fast.com of the My BT speed test are measuring the throughput - there is no point is testing line speed as it's fixed (you either have a connection at the specified rate, or you don't have a connection at all).
You mention that your main problem is Netflix dropping out occasinally, and that your BT TV box is connected via an ethernet cable to the Hub. This means that WiFi cannot be your issue, and the problem must either be congestion or a fault/misconfiguration. Even if your local optical network is completely maxed out you would still be getting roughly 80 Mbps, which is way more than needed for a 4K Netflix stream, so it seems very unlikely that congestion is the problem (unless it's at the Netflix end).
You mention that your Hub has been replaced - what about the BT TV box?
The Hub has been replaced but not the BT Box, although this was obviously working without any issues, prior to moving to the bungalow.