Google cloud engine external access issue - node.js

Question

I'm new to Google cloud platform and I didn't understand why I cannot reach a node.js instance running on a new VM.
Node is running on port 8084 through app.listen('8084', "0.0.0.0")
Firewall rules are the following:
gcloud compute firewall-rules list
NAME NETWORK DIRECTION PRIORITY ALLOW DENY DISABLED
default-allow-http default INGRESS 1000 tcp:80 False
default-allow-https default INGRESS 1000 tcp:443 False
default-allow-icmp default INGRESS 65534 icmp False
default-allow-internal default INGRESS 65534 tcp:0-65535,udp:0-65535,icmp False
default-allow-rdp default INGRESS 65534 tcp:3389 False
default-allow-ssh default INGRESS 65534 tcp:22 False
node-8084 default INGRESS 999 tcp:8084 False
netstat:
netstat -na | grep LISTEN
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:8084 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:34339 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:8998 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:65001 0.0.0.0:* LISTEN
tcp6 0 0 :::970 :::* LISTEN
tcp6 0 0 :::980 :::* LISTEN
tcp6 0 0 :::22 :::* LISTEN
tcp6 0 0 :::922 :::* LISTEN
I can reach the VM via SSH (port 22) but not through http://35.206.91.238:8084/medical on Chrome. 35.206.91.238 is the external IP showed by google cloud console.
Node.js presents no errors (and no requests).
main code is
var app = express();
app.get('/medical', function(request, response){
if( request.query.q )
run(request.query.q, function(results, queries) { parseResult(q, results, queries, response) } );
})
app.listen('8084', '0.0.0.0')
console.log('Server started on port 8084');
exports = module.exports = app;
Wireshark traffic is only
Only SYN is passing, chrome says "35.206.91.238 refused to connect."
Node is executed manually from shell and doesn't report any error after "Server started on port 8084".
Any idea