Site Showing IP address Before domain name

I’m running WP on a 123-Reg server, and when I set up the site I noticed that the IP address of the website is appearing before the domain, eg. https://10.20.64.12/mysite.co.uk/

I did change my URI etc in the setting of WordPress to my domain, https://ewanstevenson.co.uk/ but then when I went into my login for WP it wouldn’t log me in, it just came back as a blank form, and then after trying again I got a server error, and the page wouldn’t even load.

Any suggestions as to how I can fix this? I’m a bit of a newbie, so be warned.

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