Блокирующие подключения Azure NAT

Когда я пытаюсь подключиться к порту на общедоступном IP-адресе узла, в 50% случаев Azure не отвечает, и Nmap помечает его как «отфильтрованный».

Когда я пытаюсь подключиться к тому же порту с узла с помощью localhost, он работает в 100% случаев.

Я постоянно наблюдаю такое поведение в Azure, но никогда в AWS и DigitalOcean.

Есть предположения?

Nmap done: 1 IP address (1 host up) scanned in 3.23 seconds
root@AZURE_HOST:~# nmap -Pn -p 28015 AZURE_PUBLIC_IP

Starting Nmap 6.40 ( http://nmap.org ) at 2015-11-11 17:36 UTC
Nmap scan report for AZURE_PUBLIC_IP
Host is up (0.0012s latency).
PORT      STATE SERVICE
28015/tcp open  unknown

Nmap done: 1 IP address (1 host up) scanned in 3.15 seconds
root@AZURE_HOST:~# nmap -Pn -p 28015 AZURE_PUBLIC_IP

Starting Nmap 6.40 ( http://nmap.org ) at 2015-11-11 17:37 UTC
Nmap scan report for AZURE_PUBLIC_IP
Host is up.
PORT      STATE    SERVICE
28015/tcp filtered unknown

Nmap done: 1 IP address (1 host up) scanned in 3.23 seconds
root@AZURE_HOST:~# nmap -Pn -p 28015 localhost

Starting Nmap 6.40 ( http://nmap.org ) at 2015-11-11 17:37 UTC
Nmap scan report for localhost (127.0.0.1)
Host is up (0.000088s latency).
PORT      STATE SERVICE
28015/tcp open  unknown

Nmap done: 1 IP address (1 host up) scanned in 1.06 seconds
root@AZURE_HOST:~# nmap -Pn -p 28015 localhost

Starting Nmap 6.40 ( http://nmap.org ) at 2015-11-11 17:37 UTC
Nmap scan report for localhost (127.0.0.1)
Host is up (0.000070s latency).
PORT      STATE SERVICE
28015/tcp open  unknown

Nmap done: 1 IP address (1 host up) scanned in 1.08 seconds
root@AZURE_HOST:~# nmap -Pn -p 28015 localhost

Starting Nmap 6.40 ( http://nmap.org ) at 2015-11-11 17:37 UTC
Nmap scan report for localhost (127.0.0.1)
Host is up (0.000066s latency).
PORT      STATE SERVICE
28015/tcp open  unknown

Nmap done: 1 IP address (1 host up) scanned in 1.05 seconds