Connecting to internet via another router

[David Partridge]

I'm changing ISP, and in order to get the digital phone service they provide, I believe that I need to use their router (Fritz!Box 7530) as the main access point to the WAN (internet). However I still want to connect all my network devices to the RT-AC86U that's running AsusWRT-Merlin which is running an OpenVPN client - can I designate one of the LAN ports as connecting to an external router?

The Fritz!Box will allow connection to the net via another router though how this works in IP address terms is unclear to me - will Merlin also allow that?

Thanks, David

 

[Tech9]

You may have to run your equipment in double NAT behind ISP provided equipment. If you have access to the ISP equipment settings use port forwarding or DMZ your Asus WAN IP and your VPN Server will be fine. What won't work is UPnP with private WAN IP on your Asus router.

See this if you need UPnP:

Solved - UPnP doesn't work on CGNAT/Double NAT

On one of my networks running RT-AC86U it has CGNAT. But my ISP allows hole punching in firewalls using protocols like UPnP and PCP. When I enable UPnP and try hole punching with PlayStation or qBittorrent, I get this error in the log: miniupnpd: private/reserved address 100.x.x.x is not...

www.snbforums.com

 

[David Partridge]

Let me start over.
I'm trying to connect my AC86U to the Zen provided Fritz!Box (FB for short in the rest of this post) The FB has to be the primary router for Zen's telephony support to work (they've locked out the access to the telephony settings).

In the initial case I tried to leave the AC86U in Router mode and change the WAN access to use an Automatic IP on Lan port 1 which I connected via ethernet cable to a lan port of the FB. That refused to work saying it wasn't connected.

What I want is for the AC86U to be connected to the FB via an ethernet cable. I want it to have a different IP address range from the FB (which is currently using 192.168.178/24) and to route all traffic from its IP addresses (192.168.129/24) to the FB and on to the big bad world. I want to have the AC86U as the only device connected to the FB. All other devices to connec to the AC86U.

What do I need to do on the AC86U to accomplish this?
Thanks
David

 

[ColinTaylor]

In the initial case I tried to leave the AC86U in Router mode and change the WAN access to use an Automatic IP on Lan port 1 which I connected via ethernet cable to a lan port of the FB. That refused to work saying it wasn't connected.

Leave the AC86U in router mode and connect its WAN port to one of the LAN ports on the FB.

 

[David Partridge]

Setting Automatic IP and using the WAN port did the job - thank you I've been tearing my hair out!

 

[Tech9]

This is the double NAT setup. If you need port forwarding come back for help.

 

[David Partridge]

Followup question do I leave NAT enabled on the AC86U or not?

This is the double NAT setup. If you need port forwarding come back for help.

Dumb question - how do I know if I need that? I do use BitTorrent on Windows and Transmission on Linux if that's relevant ...

 

[David Partridge]

Followup question do I leave NAT enabled on the AC86U or not?

 

[Tech9]

Leave NAT enabled, your devices connected to AC86U as usual, do your normal thing and see if everything is working as expected.

 

[GSpock]

This is the double NAT setup. If you need port forwarding come back for help.

Hi, trying to learn: in this set-up, can the AC86U be in DMZ while nat & firewall enabled ? thx

 

[Tech9]

Yes. Asus WAN IP in ISP device DMZ.