I have just reported that I am experiencing poor broadband speed on all devices within my house. As I've reported this in the past I was aware of the process and prior to the Chat Session switched all devices off and connected to the hub with an ethernet cable. The BT representative talked me through the Speedtest checks and ran diagnostics to identify the problem, however these weren't as detailed as I've had in the past. As you can see below the reason for the slow speed to my property was the ethernet cable linking my laptop to the hub !!! I find this suprising.
[03:28:06 PM] xxxxx: I am done with my diagnostics and I am going ahead and sending the ethernet cable to you which is going to solve your slow speed issue. [03:29:27 PM] ME: Ethernet cable between socket and hub or hub and PC? [03:30:06 PM] xxxxx: between hub and PC. [03:30:12 PM] xxxxx: let me place the order for you [03:30:53 PM] ME: But that won't resolve speed issues with other devices connected to hub [03:33:55 PM] xxxxx: Connect the 1 device with the ethernet cable and if it will give you the right speed, then you will get the same on other devices as well.
Does this make sense to anyone or have I been fobbed off by the infamous BT customer service?
You run it from the command line with one PC as the receiver and the other as the sender. On the receiver you enter iperf3 -s, and on the sender you enter iperf3 -c <ip_addr_of_receiver>.
You don't say which hub you have, but the HH5 (A and B) and Smart Hub have 4 ports supporting up to Gigabit Ethernet speed. If the PCs both have Gigabit Ethernet NICs you should expect to achieve speeds of ~900 Mbps or higher; if one or both only have Fast Ethernet NICs then expect ~90 Mbps. If the cable is defective then throughput would be significantly lower.