When setting compatibility mode in IE 11 it wants to add our whole domain (somedomain.co.uk) but we don’t want every site (*.somedomain.co.uk) to be covered by this. We want just sharepoint.somedomain.co.uk and not www.somedomain.co.uk to be rendered using compatibility mode.
You can use Group Policy to enforce compatibility view for a specific subdomain.
Press Win + R, type gpedit.msc and press OK to launch Group Policy Editor.
The policy can be found in Computer or User Configuration > Policies > Administrative Templates > Windows Components > Internet Explorer > Use Policy List of Internet Explorer 7 sites.