netbox-community-netbox/netbox/templates/dcim/inc/cable_termination.html

<table class="table table-hover panel-body attr-table">
    {% if termination.device %}
        {# Device component #}
        <tr>
            <td>Device</td>
            <td>
                <a href="{{ termination.device.get_absolute_url }}">{{ termination.device }}</a>
            </td>
        </tr>
        <tr>
            <td>Component</td>
            <td>{{ termination }}</td>
        </tr>
    {% else %}
        {# Circuit termination #}
        <tr>
            <td>Provider</td>
            <td>
                <a href="{{ termination.circuit.provider.get_absolute_url }}">{{ termination.circuit.provider }}</a>
            </td>
        </tr>
        <tr>
            <td>Circuit</td>
            <td>
                <a href="{{ termination.circuit.get_absolute_url }}">{{ termination.circuit }}</a> (Side {{ termination.term_side }})
            </td>
        </tr>
    {% endif %}
</table>