@HMHK This seems to be normal behaviour. I spent months talking to support about this involving our firewall vendor as well. The agent uses port 993 which is IMAP usually, I dont think firewalls seem to like the Meraki client because of this.
After spending almost 4 months going backwards and forwards we ended up dropping SM for our Mac clients in favour of JAMF. I know others in the forum have done the same.
SM works perfectly with our iOS devices its only MacOS devices that were affected.
Meraki CMNO, Ruckus WISE, Sonicwall CSSA, Allied Telesis CASE & CAI