Block whatsapp

Hi all, we have a guest wifi network and would like to block whatsapp on the network.

If i enforce a layer 7 rule, it does block whatsapp when using the web browser, but it does not block the app from working. Creating content categories rules also again does not block the app from working.

I have also tried blocking Facebook and this does not do anything. I have done a packet capture and all IP`s point to facebook.

If i create "Block URL Lists" again it works when using a web browser, bit it does not block the actual usage on the app.

As a last effort i can block all Facebook IP ranges, but that is just going to flood by firewall rules , because there are a LOT of facebook IP ranges.

We are using Meraki wireless and Meraki MX , also integrated with Umbrella.

Any suggestions welcomed.

Thank you