Nothing has changed. Does any of this direction from the notification service create a new idea?
if you did not get it, something is still blocking on your end
For receiving notifications
If your organization has a firewall that restricts the traffic to or from the Internet, you need to configure it to allow connectivity with FCM in order for your client apps to receive messages.
FCM (Google Android and Chrome Push Notifications)
The ports to open are: 5228, 5229, and 5230. FCM typically only uses 5228, but it sometimes uses 5229 and 5230. FCM doesn't provide specific IPs, so you should allow your firewall to accept outgoing connections to all IP addresses contained in the IP blocks listed in Google's ASN of 15169. From the "Firewall" note: https://firebase.google.com/docs/cloud-messaging/concept-options