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Old June 16th, 2012, 08:40 PM
ammotrup ammotrup is offline
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Default AT&T IP Passthrough Incompatibility

I recently upgraded from AT&T DSL to the Uverse internet only. This is not the VDSL but ADSL2+. Because of security and authentication, only AT&T modems can be used. There is no bridge mode and the recommended method is IP passthrough which allows the router to share the public IP address

I changed the WAN setup on the DGND3700 to the wan ethernet port and set the router for DHCP and the NVG510 to IP passthrough mode (DHCPS-dynamic). The public IP address assigned has a host (255.255.255.255) subnet mask instead of the normal network subnet address. In this configuration, the DGND3700 receives the public address and gateway but can't ping the gateway or DNS server (VG510 address).

If I connect a Windows PC to the NVG510 in the same setup, I get the same DHCP values but the PC can communicate successfully.

If I try to set the wan address manually using the host subnet mask (255.255.255.255), I get an error that it is an invalid mask (Gateway not on same network). When I use a valid network subnet mask (255.255.252.0), communication is successful. Also, I tested with a different AT&T modem that gives a different mask (255.255.252.0) and works properly.

AT&T has been no help and refer to the same knowledge base articles and only offer paid support when using third party hardware. I've opened a ticket with Netgear but they also only offer paid support after the initial 90 days.

I know the problem is the subnet mask but other routers and equipment can utilize the host subnet mask (Windows PCs and other router manufacturers).

Most users of the DGND3700 are not utilizing the ethernet wan port so this problem is probably no very common. I only received the standard canned reply form Netgear on how to connect and configure wan access including the complusory reset. I don't know how other models of Netgear routers play nicely with the NVG510. Maybe some of the local experts have some input.
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  #2  
Old June 17th, 2012, 07:31 AM
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Scubbie Scubbie is offline
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Default Re: AT&T IP Passthrough Incompatibility

Sadly the WAN Ethernet port is not fully capable of working as it should.

There are many specific Cable functions which have not been enabled with this router.
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Old June 17th, 2012, 07:58 AM
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Default Re: AT&T IP Passthrough Incompatibility

http://forums.att.com/t5/Features-an...e/td-p/2890841


seems there is bridge mode.
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Old June 18th, 2012, 08:52 PM
ammotrup ammotrup is offline
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Default Re: AT&T IP Passthrough Incompatibility

There is no real bridge mode in the NVG510 (No ATM transport) but the IP passthrough is the closest feature. Most firewall functions are disabled and avoids double NATs. The real problem is that the DHCP values sends an unuseable (At least for Netgear) mask. Manually configuring the address overcomes this but if the public address of the router changes, the internet connection is down until the Netgear is reconfigured. I purchased the DGND3700 specifically because it was adaptable if I changed from DSL service.
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Old June 18th, 2012, 09:13 PM
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Default Re: AT&T IP Passthrough Incompatibility

use DGND3700 as access point instead. ..
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Old June 20th, 2012, 08:48 PM
ammotrup ammotrup is offline
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Default Re: AT&T IP Passthrough Incompatibility

If I wanted an access point, I would have purchased an access point. The AT&T router has a N300 WLAN which I have disabled. I want to use the router/firewall functions of the Netgear as the NVG510 only has basic functions available. According to the AT&T support community, other brands of routers are playing nice with the AT&T router in the same exact configuration that I am trying to use. I have an open ticket with support for this problem and they also recommend the use of a expensive router as a simple access point.

I have another open problem since 1/1/2012 with no response for the last four months except for automated responses to my request for updates. This included swapping hardware for an obvious software problem.

My experience with Netgear support has shown the company to be totally unresponsive to customer problems. Since we don't have the same consumer protections as the UK, I am stuck with an unuseable device with no recource except for warranty service which is not being provided.
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Old June 20th, 2012, 11:12 PM
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Default Re: AT&T IP Passthrough Incompatibility

just replace the NVG with other DSL unit with ATT such as their motorola DSL modem/gateway that can do bridge mode
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Old June 21st, 2012, 09:49 PM
ammotrup ammotrup is offline
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Default Re: AT&T IP Passthrough Incompatibility

AT&T no longer has a bridge mode due to the changeover from ATM to IP on the ADSL2+ link. The mandatory certificate authorization (dot 1x) only works with AT&T provisioned equipment. The change in transport on the WAN link makes Uverse a different service than the standard DSL. None of the older DSL modems are compatible with the Uverse (ADSL2+ or VDSL). In reality, the entire problem is a simple subnet mask problem. I have been a certified network engineer since 1995 so I can speak from experience that this would be easy for either AT&T or Netgear to fix with a simple software change. But so far, neither company seems to care about their customers.

I wil continue to use the static configuration and hope for long DHCP lease times. If the network goes down, I'll reconfigure.

My responses from tech support have been less than helpful as this is not listed on their scripts.
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