Moved into new build with Fibre900 capabilities, Since contract started on the 9th, i've yet to see anything over 300Mbps, via Wifi, i've used, Xbox Series X, Iphone 8+ Ipad 6th Gen and via wifi nothing over 300Mbps, i've got and old laptop but ethernet caps at 100 and it just reads 100, is the 450 Min guarantee hardwired or both HW and Wireless?
The 100mb sounds like old ethernet card which only capable of 100mb not the newer card 100/1000mb so not proper test
I think as other people have said on other threads, the speed guarantee is to your Hub. That would make sense, because beyond that, it's hard for BT to guarantee anything, as you own all of the equipment and infrastructure after the Hub, which is all massively variable.
It seems fairly likely that the 300 mbps you are getting over wifi is you hitting the limits of your wifi. On Wifi 5 devices, the best you can really hope for is 450-480 mbps in fairly ideal conditions. If you are in the 300 mbps range over wifi 5, then that's quite normal. Wifi 6 will give you faster speeds, but only if the router/mesh is Wifi 6 AND your devices are Wifi 6. None of the devices you have listed support wifi 6.
As for your wired tests, as you are getting 100 mbps, as @imjolly said, it sounds like your ethernet card is not gigabit. Your old laptop is probably old enough to be from a time before gigabit was the standard for laptop ethernet cards. You can solve that by buying a USB 3 to gigabit ethernet adaptor. Make sure it is USB 3.
Until you can properly test via wired ethernet on a gigabit enabled interface, none of the tests you are doing or will do are going to get anywhere near the 900 mbps you are hoping for. Once you have a proper gigabit test environment in place, if your speed tests are pegged at 300 mbps over ethernet, then you may be on the wrong package.
A quick follow up to my previous post...
Are you able to plug your XBox Series X into the SmartHub directly with an ethernet cable and then run a speed test over ethernet with it? That should let you see some faster speeds.
Note that you may not see the full 900 mbps though, as I'm not sure the XBox test servers will likely limit test speeds. I just ran one on my XBox One and got 770 mbps, whereas I can get 900 mbps on speedtest.net or fast.com all day long on my laptop.
I have a Cat 7 Ethernet cable coming this afternoon will hardwire it and see if it makes a difference! Your post was very informative thank you!
Good luck. Let us know how it goes.
One more follow up...I did mention earlier that you need to make sure any USB to gigabit ethernet adaptor you buy is USB 3. However, I should have also said that you need to make sure your laptop has a USB 3 port. It came to mind when I was thinking about how old your laptop possibly is, as with it not having gigabit ethernet as standard, it could well be from a time before USB 3 was standard on laptops too. If your laptop only has USB 2 ports, using a USB 3 to gigabit ethernet adaptor will top out at 400 odd mbps.
Your best bet is the ethernet cable you are receiving today to hardwire your XBox Series X in.