Hi,  @bad421 

Thank you for posting your on our business forum.

To better assist you with troubleshooting, we need some further clarification on your issue:

To confirm first: is the problem you encountered that the DNS proxy configured on your Post machine becomes unavailable when the AT&T router is operating? Could you also elaborate on the specific symptoms of the proxy issue on your Post machine?

Could you please help check the following items and provide relevant information for us:

• Have you tried running a test with only the AT&T router active, to check whether the Post machine works properly ?
• Have you attempted connecting your Post machine to the Comcast router to verify if it can work correctly in that setup?
• Would you be able to provide an overview of your current network topology?
• Do you use the ER707-M2 exclusively for automatic failover between WAN 1 and WAN 2? Are there any other additional configurations deployed on this device?

Thank you for your cooperation.

  @Jeremy_12 

Hello Jeremy

Thank You for the response to my post.

I have an AT&T router / modem (currently configured as a router) conected to the WAN/LAN 2 Port of the ER-707-M2.  It is on all of the time.  The ER-707-M2 connects to the LAN.

With the exception of the "POS" (pont of sale) sytem ALL of the other devices on the LAN continue to function just fine when comcast dies.  Fail over is flawless.  The ER-707-M2 is used exclusively to provide fail-over to AT&T when comcast dies.  

I can completely unplug the comcast router from the ER-707-M2 and everything else on the lan will continue to run without missing a beat.  The POS system works through the ER-707-M2 and comcast router on WAN 1.

I will write back with the actual proxy error and I will also provide a topology diagram.

Thank You for now

Bad421

  @bad421 

What are you setting as the DHCP assigned or Static assigned DNS address on the clients?  are you setting them to the externl DNS IP or are you setting them to your ER707 gateway IP ?  Do you have DNS proxy enabled on the ER707 ?

  @GRL 

Hello

Right now we are having a hard time getting a hold of the POS tech.  Needless to say the business owner is a bit reluctant to change anything on the POS because it works just fine on Comcast.  I believe the POS DNS settings are static.  Up until this morning the ER707 did not have anything set for the LAN DNS.  This morning I set the LAN DNS to 8.8.8.8 and 8.8.4.4.  We still lost connectivity to the POS when we switched over to AT&T.

Can you please direct me to the configuration page where I can check the setting for DNS Proxy?

I can try cutting the POS directly to the AT&T modem but I don't see what that will prove at this point. 

I will write back when I can determine the status and setting for DNS on the POS.

By the way, the site (front end) I am trying to reach (when cut over to AT&T) lives on the Google DNS server.  This chat wont allow me to post it.

Very Best Regards

Barry