scanning ports on WFADevice.

I recently  upgraded my internet connection and wifi router

In order not to add all my devices onto the new router I changed the network name & password to the old router.

Since the update, the firewall notifies me the  Sonos devices are scanning ports on WFADevice.

 Questions

1 What does this message mean

2 Is it serious?

3 How to stop the firewall from reporting