WordPress site is slow using BT Broadband Wifi

I have a WordPress Website (www.abstractmarketing.co.uk) which is very slow to open when I use Wifi at home on both my PC and my partner’s PC. We also tested it in the iPad, iPhone and Android Nokia device. Again it is extremely slow to download with WiFi.

I use my Vodafone 4G connection at home to view my website on all devices. This is super quick.

Currently, it is a terrible experience and one which I would not like my business prospects to experience as they will give up waiting for the page to appear.

I have asked other people (not on BT Broadband) about their experience and they say it is fine. They were in the UK and abroad.

My parents have the same BT Hub as myself and they have the same slow download speed as me for this particular site.

Neither myself nor my parents experience this problem with other websites.

Is this issue something that is common with others using BT Broadband Home Hub?

I am on Windows XP, using Chrome and Edge.

Is there something we should change somewhere (hub, in WordPress) ?

The page I need help with: [log in to see the link]