[ale] Why would a uverse ethernet work but not a switch?

Tue Apr 9 21:47:06 EDT 2019

Interesting concept, but that doesn't explain why it was working for a 
month or more and just now failed.  Also, it does not matter which port on 
the router I use..  In all cases the TV works but the switch does not..  At 
least, it does not when I include the building wiring.  If I move the 
switch to the router and plug it into the same port (unplugging the other 
room) the switch works fine.  So I do not think it is the VLAN.
I think it is the wiring.
I just don't know what would cause the TV box to work but the switch not 
work over the building wires.

-derek
Sent using my mobile device. Please excuse any typos.
On April 9, 2019 8:27:24 PM Alex Carver via Ale <ale at ale.org> wrote:

> I believe that AT&T has been VLANing the TVoIP data.  An ordinary switch
> that doesn't have VLAN capability may not be able to handle the mangled
> 802.1Q tagged packet so it will just dump it on the floor instead of
> routing it onward.  This would be why the Uverse box direct to the wall
> works but not through the switch.
>
> You would have to sniff the packets to see what VLAN the TVoIP data is
> on and what VLAN the normal connection to your router is on (this one is
> most likely untagged) then replace your switch with a VLAN capable unit
> and set up the ports accordingly.
>
> I have an AT&T modem as well (though my ATA is in the modem rather than
> external) and occasionally in the logs I do see messages about VLANs.
> However, I don't get TV service over the wire, I have satellite so I
> don't have a TV box to play with.  My parents also have AT&T but their
> TV box is wireless and connects to a wireless adapter plugged into the
> modem so that might be another way out.
>
> On 2019-04-09 16:08, Derek Atkins via Ale wrote:
>> Alan,
>>
>> Thank you for playing, but you are completely overthinking the problem
>> (and not paying attention to what my problem is).
>>
>> First, there is an AT&T router that provides me a local 192.168 network
>> and yes, it NATs, but that is irrelevant.
>>
>> It has 4 RJ45 ports and Wifi.
>> One port is connected to the local Uverse TV box.
>> A second port is connected to my ATA phone.
>> A third port is open.
>> The fourth port is connected to the building wire, which is connected to
>> another room.  In that other room, if I connect my Uverse TV box directly,
>> it works.  And up until a week ago, if I connected my switch and then
>> connected the Uverse Box and my Smart TV to the switch, it all worked.
>>
>> HOWEVER, as of now, the switch doesn't sync when connected.  This appears
>> to be a layer 2 issue, not a layer 3 issue.  My devices don't get an IP
>> address from my local router.
>>
>> If I connect the Uverse Box directly to the wall (without the switch),
>> then the layer-2 syncs just fine.
>>
>> I admit I have not tried connecting just the smart TV.
>>
>> However, the switch will not sync to the router.  The link lights just
>> flash but don't stay on.
>>
>> What I don't understand is why the uverse box will happily sync up on
>> layer 2 ethernet where my switch wont?
>>
>> -derek
>>
>>
>>
>> On Tue, April 9, 2019 5:22 pm, Alan Hightower via Ale wrote:
>>>
>>> I'm sure Uverse isn't providing multiple routable (real) IPv4 addresses.
>>>   So the router is likely NAT masquerading any downstream devices that
>>> try to initiate an outbound connection to the rest of the world.  In
>>> fact, it's very likely both your local router and an upstream network
>>> router are both NAT masquerading as there isn't any reason to have
>>> routable IPv4 addresses anywhere in AT&T customer infrastructure.
>>>
>>> So my guess is AT&T pushed a firmware update to the router to change the
>>> masquerade policy.  Why?  Because they are AT&T of course.
>>>
>>> If your SLA covers providing you with general Internet service via the
>>> wired router path, take it up with AT&T and have patience.  If they
>>> expect you to only get it via WiFi from the router, take it up with AT&T
>>> and prepare for failure.  Also if the later, you could turn a close
>>> proximity wifi client connection into bridge wired ethernet with a
>>> number of commodity devices.
>>>
>>> You can do some poking around and report back.  Plug a PC into the
>>> switch and see if you get a DHCP lease from the router.  Report back the
>>> lease details if any.  And if you do get a lease, make sure you can ping
>>> the default route and perform a traceroute to a North Star such as
>>> 8.8.8.8 and report back.
>>>
>>> -Alan
>>>
>>>
>>> On 2019-04-09 15:15, Derek Atkins via Ale wrote:
>>>> Hi,
>>>>
>>>> I'm temporarily living in an apartment while my house is being
>>>> renovated, and we have AT&T Uverse here.  Uverse uses ethernet for the
>>>> "remote" TV box, and until a week ago I had installed a switch to allow
>>>> me to plug in both the uverse box and my smart tv (the wifi there is
>>>> spotty).  See diagram:
>>>>
>>>> [router] - [wall] - [building wiring] - [wall] - [switch] - TV and
>>>> Uverse
>>>>
>>>> I was gone for a week and when I came back the switch was no longer
>>>> syncing to the router, so neither the TV nor Uverse were working.  At
>>>> first I thought it was the switch that went bad (there was a power
>>>> outage when I was gone), so I ordered a replacement.  However, the
>>>> replacement switch also does not work.  What is strange is that if I
>>>> plug the uverse box in directly to the wall it works fine.  Moreover,
>>>> if
>>>> I plug the switch directly into the router using a local patch cord it
>>>> works there.  So the only time the switch fails is when it uses the
>>>> building wiring.
>>>>
>>>> As I said before, I'm in an apartment so don't really have access to
>>>> the
>>>> building wiring.  I can ask the building management, but I suspect they
>>>> will foist me off to AT&T.  And if I go to AT&T, I suspect they will
>>>> say
>>>> they don't support switches -- and will ignore me because their Uverse
>>>> box works just fine.
>>>>
>>>> SO...  Any ideas where I go from here?  They are only using 4 wires (2
>>>> pairs) for the in-wall wiring, but that should be fine even for my
>>>> little netgear switch.  At least, it was until a week ago.  I don't
>>>> understand why the Uverse box works but a switch wont.
>>>>
>>>> Any ideas?
>>>>
>>>> -derek
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>>
>>
>
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