Test site on different server

I’ve been experiencing problems with my host with my WordPress sites running on Windows so in an attempt to resolve they set me up with an account on one of their Linux servers.

Without changing DNS, I have FTP’d all relevant files across, changed the DB_HOST in wp_config.php so it’s looking at the live domain and am browsing the test site via an IP address.

Currently it’s reporting errors and things like the nav are redirecting me to the live url. Does anyone know what I need to change so that the test site sees the IP address rather than the domain as the host? Thanks!