My current network setup (which works):

A) ISP-provided modem/router (Main): Fiberhome HG180 VDSL w/ voip


  1. 2 RJ11 ports (1 for DSL and 1 for landline phone)
  2. 4 lan ports and NO wan port
  3. Connected to internet via PPPoE
  4. Internal IP Address is
  5. NAT and DHCP turned on
  6. Only the secondary router is connected to the LAN port
  7. Has bridge mode but ISP does not seem to know how I can set it up correctly

B) My own router (Secondary): ASUS RT-AC68U


  1. Wan port connected to LAN port of main router
  2. Connected to internet via the main router
  3. Internal IP Address is (so different subnet)
  4. DHCP turned on and manages the rules/reservation of connected devices
  5. Detects double NAT and does not allow DDNS because of this


I need to be able to access my NAS and RPi on the internet which is connected to the secondary router. I can't connect them to the main router because of physical and location issues. And I also want my secondary router to control DHCP as its interface is easier

My issues:

  1. My ISP is no help at all as they only know how to configure their routers based on their SOP
  2. I tried configuring it based on DIFFERENT settings I saw being discussed on forums but its either I don't know what I'm doing or I can't seem to find the right combination of the recommendations.

Hope somebody can help.

closed as off-topic by Gerald Schneider, womble Oct 11 at 21:54

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on Server Fault must be about managing information technology systems in a business environment. Home and end-user computing questions may be asked on Super User, and questions about development, testing and development tools may be asked on Stack Overflow." – Gerald Schneider, womble
If this question can be reworded to fit the rules in the help center, please edit the question.

The ISP's router can do NAT and DHCP (for its local subnet). Your router should be configured as router with DHCP (for its local subnet) but not with NAT.

Next the ISP's router will need a static route for (your internal subnet) and point it to the IP address of your router. This will be easier if you give your router a fixed IP address instead of having it assign an IP address from the ISP's router. For example, give it the IP address instead of it getting a random IP address from a pool.

Also, your own router should have a default route pointing towards the ISP's router, meaning a route for pointing to

That should fix your issues.

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