moby: [swarm] routing mesh not working as expected

Output of docker version:

Client:
 Version:      1.12.0
 API version:  1.24
 Go version:   go1.6.3
 Git commit:   8eab29e
 Built:        Thu Jul 28 21:04:48 2016
 OS/Arch:      darwin/amd64
 Experimental: true

Server:
 Version:      1.12.0
 API version:  1.24
 Go version:   go1.6.3
 Git commit:   8eab29e
 Built:        Thu Jul 28 23:54:00 2016
 OS/Arch:      linux/amd64

Output of docker info:

Containers: 2
 Running: 2
 Paused: 0
 Stopped: 0
Images: 1
Server Version: 1.12.0
Storage Driver: aufs
 Root Dir: /mnt/sda1/var/lib/docker/aufs
 Backing Filesystem: extfs
 Dirs: 11
 Dirperm1 Supported: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: host null bridge overlay
Swarm: active
 NodeID: 2jml8zh2ap8gnw3ghchc03g09
 Is Manager: true
 ClusterID: 1h8ug9o7h7ihgspy7wmgr7z68
 Managers: 2
 Nodes: 5
 Orchestration:
  Task History Retention Limit: 5
 Raft:
  Snapshot interval: 10000
  Heartbeat tick: 1
  Election tick: 3
 Dispatcher:
  Heartbeat period: 5 seconds
 CA configuration:
  Expiry duration: 3 months
 Node Address: 192.168.99.100
Runtimes: runc
Default Runtime: runc
Security Options: seccomp
Kernel Version: 4.4.16-boot2docker
Operating System: Boot2Docker 1.12.0 (TCL 7.2); HEAD : e030bab - Fri Jul 29 00:29:14 UTC 2016
OSType: linux
Architecture: x86_64
CPUs: 1
Total Memory: 995.9 MiB
Name: master1
ID: XFBC:QIPK:ZJH5:MGSZ:D6IA:32XG:TUHL:6E43:HXOQ:FVLW:OY64:HWD4
Docker Root Dir: /mnt/sda1/var/lib/docker
Debug Mode (client): false
Debug Mode (server): true
 File Descriptors: 55
 Goroutines: 212
 System Time: 2016-08-04T08:18:26.116262192Z
 EventsListeners: 2
Username: rogaha
Registry: https://index.docker.io/v1/
Labels:
 provider=virtualbox
Insecure Registries:
 127.0.0.0/8

Additional environment details (AWS, VirtualBox, physical, etc.):

Steps to reproduce the issue:

1. docker service create --name service1 --network whoami-net -p 8000 jwilder/whoami
2. docker service scale service1=3

Describe the results you received:

rogaha@Robertos-MacBook-Pro:~$ curl http://192.168.99.100:30000/                                                                                                            1:18:26
I'm a2531712ae05
rogaha@Robertos-MacBook-Pro:~$ curl http://192.168.99.103:30000/                                                                                                            1:34:14
curl: (52) Empty reply from server
rogaha@Robertos-MacBook-Pro:~$ curl http://192.168.99.104:30000/                                                                                                            1:35:08
curl: (52) Empty reply from server

Describe the results you expected:

rogaha@Robertos-MacBook-Pro:~$ curl http://192.168.99.104:30000/                                                                                                            1:18:26
I'm a2531712ae05
rogaha@Robertos-MacBook-Pro:~$ curl http://192.168.99.103:30000/                                                                                                            1:19:56
I'm b0d6d239f694

Additional information you deem important (e.g. issue happens only occasionally):