Sorry to read you are having an issue with the broadband speeds.
From checking your connection, there is a high peak time traffic fault in your area which is causing slow speeds. The reference number is F005355328 and has a review date of 25th April 2018. As this is a review date it can be subject to change.
Do you notice this issue at all times of the day or just during peak hours? If you complete a speed test on a PC/laptop through wired, is there a difference?
Offline System Update Diagnostic Tool on Xbox One: http://bit.ly/1e8bSs3 Network ports used by Xbox Live on Xbox One: http://bit.ly/1dCNLm0 xBox Support: http://bit.ly/1lE2QrK Xbox One operating system versions and system updates: http://bit.ly/1NiJS1j