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ASUS RTN66U connected to a Motorola nvg589.


ASUS RTN66U connected to a Motorola nvg589.

Hi –


Have an ASUS RTN66U connected into a Motorola NVG589.

Everything worked with the Time Warner Modem. DDNS, RDP and I could PPTP in from remote locations.

Now I get a message from RTN66U: This router may be in the multiple-NAT environment and DDNS service cannot work in this environment.


Multiple searches on web and this site have found:

One site said - Do you also have a NAT modem, maybe your modem is also a wireless AP. I had this same issue but my isp flashed my provided modem to bridge mode which resolved the issue

First attempt to find resolution did in fact give me a dual NAT. Fixed that by changing settings and turning off DHCP on the ASUS.



Have tried some of the suggestions from this site and others with no resolution.

All I get are more error messages from the nvg589.


  • Address must not be on network (

( Address conflicts with existing LAN configuration (conn[1].static)

  • Address must not be on network (

( is not the network address given subnet mask (


Tried to set up Cascaded Router and got an error so, though perhaps need to configure Public Subnet since the instructions say:

“Cascaded Router Address: The IP address for the router behind this device. The Cascaded Router Address should be in the LAN Private IP subnet range.”


And I’ll state up front that I’m not an expert at this but, know enough to be able to break things and have to put them back the way they were before tinkering. LOL


Spoke with Cisco Engineer at work and his response was ‘Good Luck, I had same kinds of issues with U-verse and that’s one of the reasons I switched back to Time Warner.’


I’m still within my 30 day evaluation and can switch back…


Looking for suggestions.




Message 1 of 10

Re: ASUS RTN66U connected to a Motorola nvg589.

You need to use IP Passthrough mode with the NVG589 so that the Asus router will get the outside IP address. Search the forum for IP Passthrough mode, you will find several step-by-step instructions.

Message 2 of 10

Re: ASUS RTN66U connected to a Motorola nvg589.

Thanks, I tried that but looks like I have to turn DHCP on the ASUS back to on and change its IP so there is a dual NAT again.
Message 3 of 10

Re: ASUS RTN66U connected to a Motorola nvg589.

Yes, you will have to turn on DHCP, but it will not be dual NAT. In IP Passthrough mode, the NVG589 will issue the outside IP address (the registered, routable public IP) to the Asus via DHCP.
Message 4 of 10

Re: ASUS RTN66U connected to a Motorola nvg589.

Half way there...


Chromecast was telling me something wrong - reconnect me. Then it worked.


DDNS Can ping externally  to RTN66U and it now reports my current ATT IP.


PPTP Almost works but fails at the last minute. Wan miniport SSTP fails.

---Strange - work inside the network - wont from outside.---


RDP "Can't connect to the remote computer." Port forwading being blocked.(?)


At one point the nvg589 stopped letting me experiment and told me 'Under control of another device'.

Have not turned off the nvg589 ports or wifi. Can reach the nvg589 and RTN66U while on Asus wifi but cant connect to RTN66U while on ATT wifi. And the ATT phone tv apps wont work on asus wifi but function on the ATT wifi.


And the other strange thing was that the IPpassthrough wouldn't work with the RTN66Us physical address but will work with the cloned address.


You would think turning off the tv and internet were a crime. As soon as I start working on the system - everyone except the dog starts crying. LOL

Message 5 of 10

Re: ASUS RTN66U connected to a Motorola nvg589.

Made one too many changes and knocked out the Internet, TV, phone and alarm. Thank God and some engineer for the reset buttons on the backs of the routers. Two ten second pushes and everything worked again. And I was so close to having it right. With the DVR recording shows my next window of oppertunity to tinker won't be for a couple of days.
Message 6 of 10

Re: ASUS RTN66U connected to a Motorola nvg589.

Found another set of instructions and they work - But the external IP wasnt passed to the RTN66U.



Tinkerd with settings and once again got the external IP to passthough to RTN66U  AND then the Uverse TV wire &  wireless TV couldn't connect. Reset Button - Blink, blink, BLINK... Going to get this to work. Smiley Happy

Message 7 of 10

Re: ASUS RTN66U connected to a Motorola nvg589.

Its time to walk away from the computer...

Got the external IP to passthrough to the asus router.

It says the DDNS is set up and working.

I can ping the DDNS from inside the network but, pings from outside wont work.

And with pings not working from outside - PPTP not going to work.


One other thing, with the ATT wifi shut off the U-Verse apps on the phone can't find the TVs.

The Tvs and phone are working and I believe the alarm is connected - can turn it on.off.


Once again so CLOSE...

Looking at the ping times tells me the router is internally looping the ping.


Where is 'Some Joe' when you need him (LOL)  Smiley Frustrated

Message 8 of 10
Accepted by topic author
Accepted by UpAllNight
‎09-30-2015 1:39 AM

Re: ASUS RTN66U connected to a Motorola nvg589.

There is an old saying about looking into a gift horses mouth...


Yesterday my wife was complaining about the ATT WIFI being off and the tv apps not working.

Turned the ATT wifi back on and while I was working on the routers, also enabled RDP on the asus.


Today - EVERYTHING works??? DDNS - PPTP - RDP.

I saved the RTN66Us config file and am doing the happy dance.


These links may help someone else:






Thanks for the MO-JOE 'Joe' - LOL.


Next battle - Having five different ATT passwords and getting mail on three different email addresses.






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Message 9 of 10

Re: ASUS RTN66U connected to a Motorola nvg589.

My Cell Phone can not connect to my WiFi . My PC works fine

Message 10 of 10
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