Is this a combination DSL Modem/Router from AT&T or do you have a separate DSL modem and router? What are the brands and model numbers of the gear you have?
Yes it's an ATT combo 2Wire 2701HG-B dsl modem/router.
You've first got to make sure that the 3808 can 'see' your router.
Look at the status lights on your router. Specifically, the port that the 3808 is plugged into. Make sure the port's status lights are lit up. If not, then your 3808 isn't even physically connected to the router. Check the cables and connections.
Ethernet light is green, currently the 3808 is the only ethernet connectiom, it's also lit at point of entry in back, when I disconnect ethernet cable both lights go out.
If that port is lit up...
Are you using DHCP on your home network? If so, the 3808 should be set appropriately. I have no idea how that's set up on the 3808, but there ought to be some sort of 'automatic' network setting. There should be a way for you to access the DHCP client list on your router. Verify that you can see the 3808 on that list. If you can't see it, then it's not connecting to your router properly.
Yes I am using DHCP, and the 3808 shows up on the router list as "connected" with a unique IP address assigned from the range of options (exactly one higher than the previously assigned address).
If you're not using DHCP, and using static IP addresses, then you need to be very sure that you're assigning the 3808 a free IP address and that the subnet, DNS, and gateway settings are correct on the 3808.
I've tried this as a workaround but I'm not sure all of the settings are correct when I attempt this, e.g., if I use the assigned IP address are the subnet, DNS, and gateway settings identical to those on the router itself, or should I use the static address assigned to the router along with above (have tried both solutions without success)?
Once you can prove that the 3808 is 'talking' to the router, then the next step is internet connectivity. Does the 3808 use a specific port? If you know, make sure the router's firewall is setup to allow it.
Not sure what this means, where is this port located, on the 3808 or router?
UPnP is a big help here. If your router doesn't support that, I'd get a new router.
For the 3808 to function, UPnP has to be disabled (thanks Denon, leave it to everyone else to work things out) on the modem/router, according to Axiom threads, Google threads, as well as Denon tech telephone support. ATT and Google threads state that the 2wire modem does not support UPnP, which begs the weird question if support is not present, can I turn UPnP off? I'm suspecting I need a new router dedicated to the 3808, not sure what is available that will be compatible with this particular ATT service.
See if your router has a DMZ feature. By putting your 3808's IP address here, it will bypass any protective firewalls. See if that works. If it does, then you've got a firewall problem. If not, then you've got some sort of general connectivity issue, and that's going to be really tricky to help with.
ATT suggested I disable the router firewall for the Denon, they call this "Allow all applications (DMZPlus mode)."
Implementation of this setting had no effect. If I'm not mistaken, what this mode does is assign the static IP address associated with the modem/router (i.e., the router labels the Denon device as the assigned DHCP address yet the IP Address is identical to the router's broadband connection IP address) to the Denon unit rather than one of the floating (?) addresses in the DHCP range of addresses.
Check your router's firmware and make sure that it's completely up-to-date. That matters. I once bought a new notebook that just wouldn't connect to my router. After hours of troubleshooting, I discovered that it was a known issue between the router and the NIC card in the notebook. A firmware update for the router was available, and it completely solved the problem.
Already checked, the firmware for the router is completely up to date, no upgrade available.
And lastly, it's possible that for whatever reason your router & 3808 just aren't going to get along. In that case you're going to need a new router. Do you have another router you could try?
Again I suspect this to be true, because I have yet to tweak my way out of a network meltdown such as this. My concerns/questions are: 1) ATT relies heavily on 2Wire modems because generally they work well and are compatible with a wide range of computers, 2) are there other DSL modems that would work with ATT, and 3) are there DSL modems that are confirmed to work with Denon.
At this point I don't need a router, just a dedicated dsl modem that is confirmed to work with att/denon 3808.
Thanks much Peter for your detailed comments/suggestions.
