wireless to wired uverse access point

Restart the wireless stb connected via Ethernet. It should connect wired with the wap on for the other tv.  Restarting the gateway may help as well. 

When switching a wireless receiver to wired reboot the gateway (pull plug for 15 secs. and let it fully reboot) to get the gateway's device tables updated to the new configuration.  Your other tv with it's wireless connection should be OK after that. 

Note, I didn't see you mention whether you rebooted the gateway or not so that's why I am mentioning it here.

You are plugging this stuff (WAP's ethernet cable and the other tv's ethernet cable) directly into the gateway as opposed to a gigabit ethernet switch aren't you? 

Let's see if I understand this:

• Ethernet from gateway to dvr.
• Ethernet from gateway to receiver.
• Ethernet from gateway to WAP.  (so at this point you have one free ethernet port if I understand this setup correctly).
• You rebooted the gateway.
• You've rebooted the WAP after rebooting the gateway (although I am not sure this is strictly necessary)
• Dvr and wireless receiver have no problem with pairing and booting up.
• You boot up the newly wired receiver and it doesn't boot? (if that's what you mean by "does not connect").  What does it say ion the screen if anything?

Does that about summarize it?  That setup should be working.  All I can suggest now is a desperation move and factory reset the gateway.  Push red button on back for at least 15 secs (or at least greater then 10 - 10 or less is a reboot like pulling the power).  Of course if you changed any settings in the gateway (e.g., wifi password) those are lost.  If this doesn't fix it I would try to get the gateway (and maybe WAP) replaced because there is nothing wrong with that setup as far as I know.

Once a wireless receiver has been paired with the AT&T WAP, you cannot connect it using its RJ45 port, unless you shut down the WAP.  The problem is that a wireless receiver's WiFi system and RJ45 port are internally bridged together -- think internal three-port Ethernet switch with the WiFi, the RJ45 port and the receiver itself connected to it.  The wireless receiver's WiFi system will always associate with the WAP, if it is available.  When the RJ45 port is then also connected, a loop will form in your network and quickly cause a broadcast storm that consumes the available bandwidth.  I am willing to bet that the performance of the wireless-only receiver is also affected to some degree.

Try this - it may work for you:  Power-off the WAP (actually power it off).  Restart the wired wireless receiver and wait for it to come up completely.  Then, power-on the WAP.  Everything should work correctly now because the wired wireless receiver should not try to associate with the WAP since it already has a functioning network connection using the RJ45 port.  However, if this receiver loses its network connectivity or restarts for any reason, the problem will reappear as it will associate with the WAP again and recreate a loop.

To fix it permanently, you will need to unpair that wired wireless receiver from the WAP so that the receiver can never establish a WiFi connection again.  Unfortunately, there is no convenient built-in method to do this.  The wireless receiver will retain its WiFi settings even after a factory reset (Power/OK/Down sequence).  Therefore, in order to make this receiver “forget” the WAP, you will need to pair it with another 5-GHz network that will never be in range again.  You can do one of the following:

1.  Have AT&T replace your WAP; the new WAP will have a different SSID.  Then pair your wireless-only receiver to the new WAP.  Do not ever pair your wired wireless receiver with this new WAP.
2. Borrow a WAP from someone who lives far enough away and pair your wired wireless receiver to it.  Then make sure that this WAP never shows up near your house again.
3.  If you have a 5-GHz WiFi network at home with WPS...  Create a new, temporary SSID on your 5-GHz network.  Pair your wired wireless receiver to this new SSID.  Then, delete the temporary SSID and restore your original home SSID.  The receiver will forever be looking for a WiFi network that will not exist so make that temporary SSID pretty obscure.

You will need to power-off your original WAP during each of the preceding three scenarios.

In fact, if you have a decent 5-GHz network and have good coverage throughout the house, you should just pair all of your wireless receivers with your 5-GHz SSID and stow that AT&T WAP.  You do not need it.  It is just one more wireless AP that sits in an inconvenient spot, pollutes the airwaves and consumes extra power.  Make sure that your home network equipment is capable of handling IP multicast and IGMP snooping.

-John

@johnc60 

If what you say is true the following should work:

• Power off the gateway, wireless receiver, and disconnect the WAP.
• Connect the wireless receiver with it's ethernet cable.
• Boot the gateway and wait until it completes it's booting process.
• Boot the wirieless-now-wired receiver. No WAP is in the picture so theoretically it should use the wired connection (maybe after it discovers no wireless is available). 
• Reconnect the WAP.  Other wireless receiver should still pair with it.

If this works will rebooting the wireless-now-wired receiver search for the WAP again in the next reboot or does it remember the most recent connection it had from the previous boot?  You say it will default back to the WAP.  But I think this needs testing.  If it is remembering the WAP pairing then I think a factory reset (disaster recovery) of the wireless-now-wired receiver should clear it unless a wireless receiver always tries to use the wireless when both wired and wireless are available.

The gateway itself is not actively involved so there is no need to reboot it. The problem is between the wired wireless receiver, the WAP and the wired network that connects these two devices.

A wireless receiver does not remember the last connection. Whenever it loses its network connectivity or after a restart, it looks for a connection. It prefers wired, if both WiFi and wired are available. However, remember that the WiFi and RJ45 ports are internally bridged. The exception to this is immediately after a restart where the WiFi port is kept disabled if the RJ45 port is active. After that, it is anyone's guess because once the receiver decides that it needs to enable the WiFi port, it will never disable it even if it does not need to use WiFi anymore. Hence, it is unstable and is unpredictable as to when a loop will suddenly appear.

The simultaneous use of both the WiFi and wired port is clearly not defined very well in the wireless receiver's design; AT&T can probably fix this with a simple firmware change. Therefore, to safely use a wireless receiver's RJ45 port, ensure that its WiFi connection can never become active. This means changing the receiver's WiFi association to a nonexistent SSID as there is no way, that I know, of to erase its WiFi configuration. As stated earlier, a "disaster recovery" reset does not clear the WiFi settings.

In practice, restarting the wired wireless receiver should make everything work properly, especially if the WAP is powered-off first, but it is a hit-or-miss prospect as any time the receiver needs to enable its WiFi, a loop occurs and the network melts down.

By the way, all of this relates to the ISB-7105 wireless receiver. I am not certain about the behavior of other models but knowing AT&T, they are probably similar.

@johnc60 If what you say is correct, why can a device connected via cat5 to a wireless stb using the wap connect to the internet?