This is not the name of your sensor (in the card):
entities:
- entity: binary_sensor.ping
Your sensors will be called:
color_thresholds:
- color: '#e45e65'
value: 40
- color: '#e0b400'
value: 30
- color: '#0da035'
value: 20
- color: '#039BE5'
value: -1
color_thresholds_transition: hard
entities:
- entity: sensor.wan_ping
- entity: sensor.lan_ping
group: false
height: 300
hour24: true
line_width: 4
name: Ping
points_per_hour: 10
show:
extrema: true
average: true
fill: fade
icon: true
labels: false
name: true
state: true
type: custom:mini-graph-card
Also your second template sensor seems to be using the wrong binary sensor. Should be:
- sensor:
- name: "LAN Ping"
icon: "mdi:speedometer"
unit_of_measurement: "ms"
state: "{{ state_attr('binary_sensor.default_gateway_ping', 'round_trip_time_avg')|round(2) }}"