This article is a reference guide for enabling port forwarding (static IP masquerade) on the NTT ONU router PR-S300SE.
Port Forwarding Unavailable
I set up a security camera and management server at my grandparents’ house and was building a VPN to enable remote maintenance from anywhere.
VPN setup requires port forwarding, but the PR-S300SE had no port forwarding option visible in its interface. I was completely stuck, so I am sharing this as a personal reference and knowledge base for others in the same situation.
Root Cause
The short answer: the connection had been silently switched to IPoE.
If the “PPP” lamp on your ONU is off, this issue likely applies to you.
What is IPoE?
IPoE is a newer connection method replacing PPPoE. Many people are familiar with PPPoE.
PPPoE routes traffic through a “network termination device” that connects the telephone network to the ISP.
IPoE, on the other hand, connects directly without going through such a termination device.
Additionally, unlike PPPoE, IPoE supports IPv6.
However, port forwarding options are limited under IPoE.
This is likely why the port forwarding (static IP masquerade) feature was hidden on the PR-S300SE.
The solution: switch from IPoE back to the traditional PPPoE connection.
Switching from IPoE to PPPoE
Unfortunately, this cannot be done online — you need to contact customer support.
OCN Technical Support: 0120-047-860 (Hours: 10:00-17:00, excluding year-end/New Year holidays)
Since my grandfather is the account holder, I assisted him during the call. (For account holders 65 and older, a relative within two degrees of kinship must be present.)
I told the operator directly: “I want to switch from IPoE to PPPoE because I need port forwarding.” They understood immediately.
About 10 minutes after the call, the “PPP” lamp lit up, confirming the switch to PPPoE.
Static IP Masquerade Setting Appears!
After the PPP lamp turned on, I accessed the admin panel again. The option “Advanced Settings” then “Static IP Masquerade” was now visible.
Port forwarding is now available. Well done!
Reference: Methods Found Online That Did Not Work in My Environment
Accessing the hidden menu at http://192.168.1.1:8888/t/ opens a page called “Deployed ISP Software.”
Some sources mention a “Static NAPT” option in the right column under IPv6, but in my environment the right column did not appear at all. (Possibly unavailable for OCN Virtual Connect subscribers.)
Reference: Port forwarding settings when switching from PPPoE to IPoE (IPv4 over IPv6)
Leave a Reply