MX Box in HA cannot ping each other

[IsraelFilho]

I have a MX cluster in HA mode. Both boxes aren't unable to ping each other WAN interfaces. I am using the WAN interfaces as source and the destination the WAN interface on the other box.

It just won't work.

Any Idea why it is like that?

Thanks

[NolanHerring]

Do you have pings allowed on WAN interface?
Check the firewall rules, you'll probably have to allow it if it is set to NONE (default).

[dalmiroy2k]

Check this documentation:

https://documentation.meraki.com/MX/Deployment_Guides/MX_Warm_Spare_-_High_Availability_Pair

Is Your Spare unit in "Passive - Ready" state? Are you using virtual uplink IPs? Nat mode? 

[PhilipDAth]

You'll need to enable ping under appliances services.

https://documentation.meraki.com/MX/Firewall_and_Traffic_Shaping/Firewall_Settings#Appliance_Service...