Re: Internet Port IP Address not matching real Internet IP Address

Sempytender · ‎2021-11-08

Hello,

I'm currently trying to solve a port forwarding issue with my Netgear Orbi (RBR750 is the reported model) and I've stumbled upon something weird:

When I go into Internet Port settings, it gives me an external IP address of 100.x.x.x and a gateway of 100.x.x.x. According to "what's my ip address", my external IP is actually 119.x.x.x. I don't have any problems using the internet etc. I have had massive issues trying to do port forwarding though - won't port forward to my NAS (for plex etc) nor to my main PC (for gaming servers etc). My internal network addresses start with the classic 192.168.1.x

It feels like a double NAT problem but I only have the one router - the netgear orbi - so I don't know how it could be that.

Can anyone suggest something? Thanks.

Extra note: I'm in Australia and our "NBN" (National Broadband Network) connection comes with a connection box but there's no way to remote into it or change any settings etc (as far as I know). There's no login/password etc.

schumaku · ‎2021-11-08

Your ISP appears to deploy CGN, Carrier Grade NAT (RFC6598: IANA-Reserved IPv4 Prefix for Shared Address Space) to overcome the shortage of public IPv4 addresses.

The NBN does only make up the transport layer, anything above is under the ISP responsibility.

Talk to your ISP, requesting a public routeable IPv4 address on your connection.

Regards,

-Kurt

View solution in original post

schumaku · ‎2021-11-08

Your ISP appears to deploy CGN, Carrier Grade NAT (RFC6598: IANA-Reserved IPv4 Prefix for Shared Address Space) to overcome the shortage of public IPv4 addresses.

The NBN does only make up the transport layer, anything above is under the ISP responsibility.

Talk to your ISP, requesting a public routeable IPv4 address on your connection.

Regards,

-Kurt

Sempytender · ‎2021-11-08

Thanks so much for a speedy reply. I will check it out. Could this be the root of all my port forwarding issues as well?

schumaku · ‎2021-11-08

Yes, of course. We have no control about the port forwarding on the ISP' CGN routers.

PS. Great explanation of the "is-situation" of your connection - made it easy to anser!

Sempytender · ‎2021-11-08

As a concluding note: Yes, this was the issue. And for 6 months, I've thought about throwing out my (brand new) Orbi routers because I couldn't get port forwarding to work.

Thanks for the assistance - saved me quite a bit of money. Was able to opt out of the CGNAT by giving my valid reasons for needing a real IP address 🙂

FURRYe38 · ‎2021-11-09

Your ISP Modem already has a built in router and wifi. This would be a double NAT (two router) condition which isn't recommended. https://kb.netgear.com/30186/What-is-Double-NAT
https://kb.netgear.com/30187/How-to-fix-issues-with-Double-NAT
Couple of options,
1. Configure the modem for transparent bridge or modem only mode. Then use the Orbi router in router mode. You'll need to contact the ISP for help and information in regards to the modem being bridged correctly.
2. If you can't bridge the modem, disable ALL wifi radios on the modem, configure the modems DMZ/ExposedHost or IP Pass-Through for the IP address the Orbi router gets from the modem. Then you can use the Orbi router in Router mode.
3. Or disable all wifi radios on the modem and connect the Orbi router to the modem, configure AP mode on the Orbi router. https://kb.netgear.com/31218/How-do-I-configure-my-Orbi-router-to-act-as-an-access-point and https://www.youtube.com/watch?v=H7LOcJ8GdDo&app=desktop

Try option #2 if you want to help with a double NAT condtion...

schumaku · ‎2021-11-09

@Sempytender wrote:

Was able to opt out of the CGNAT by giving my valid reasons for needing a real IP address 🙂

Cool. For reference, which ISP, and any price tag attached to the service?

@FURRYe38 wrote:

Your ISP Modem already has a built in router and wifi.

Nope. The IP address does talk a clear language - it's CGNAT.

FURRYe38 · ‎2021-11-09

👍

Posted JIC.

Sempytender · ‎2021-11-09

@FURRYe38 wrote:
Your ISP Modem already has a built in router and wifi. This would be a double NAT (two router) condition which isn't recommended. https://kb.netgear.com/30186/What-is-Double-NAT
https://kb.netgear.com/30187/How-to-fix-issues-with-Double-NAT
Couple of options,
1. Configure the modem for transparent bridge or modem only mode. Then use the Orbi router in router mode. You'll need to contact the ISP for help and information in regards to the modem being bridged correctly.
2. If you can't bridge the modem, disable ALL wifi radios on the modem, configure the modems DMZ/ExposedHost or IP Pass-Through for the IP address the Orbi router gets from the modem. Then you can use the Orbi router in Router mode.
3. Or disable all wifi radios on the modem and connect the Orbi router to the modem, configure AP mode on the Orbi router. https://kb.netgear.com/31218/How-do-I-configure-my-Orbi-router-to-act-as-an-access-point and https://www.youtube.com/watch?v=H7LOcJ8GdDo&app=desktop

Try option #2 if you want to help with a double NAT condtion...

Thanks for replying but this doesn't apply to my situation. It was a CGNAT at fault. Thanks anyway.

Sempytender · ‎2021-11-09

@schumaku wrote:
@Sempytender wrote:
Was able to opt out of the CGNAT by giving my valid reasons for needing a real IP address 🙂
Cool. For reference, which ISP, and any price tag attached to the service?

@FURRYe38 wrote:
Your ISP Modem already has a built in router and wifi.
Nope. The IP address does talk a clear language - it's CGNAT.

It was Aussie Broadband - no price. They have specific reasons that you can validly opt out of the service. I just told the truth - I need to port forward to my NAS and remote into my computer. He told me, great, that's valid and it was all fixed in 5 minutes after I power cycled the connection box. A way around needing a valid reason would be to pay the $5 a month for a static IP. Seems steep to me. I would just say that you need to port forward to devices on your network.