plugins/CoreHome/templates/_warningInvalidHost.twig

{# untrusted host warning #}
{% if (isValidHost is defined and invalidHostMessage is defined and isValidHost == false) %}
    {% set invalidHostText %}
        <a class="btn btn-link" style="float:right;" href="{{ 'https://matomo.org/faq/troubleshooting/faq_171'|trackmatomolink }}" rel="noreferrer noopener" target="_blank">
            <span class="icon-help"></span>
            {{ 'General_Help'|translate }}
        </a>
        <strong>{{ 'General_Warning'|translate }}:&nbsp;</strong>{{ invalidHostMessage|raw }}

        <br>
        <br>

        {{ invalidHostMessageHowToFix|raw }}
    {% endset %}

    <div style="clear:both;width:800px;">
        {{ invalidHostText|notification({'noclear': true, 'raw': true, 'context': 'warning'}) }}
    </div>

{% endif %}