Unable to connect to external IP from App Service through 2 VNETs which are peered

Peter Mello 25 Reputation points
2024-06-11T21:23:05.82+00:00

Connecting to 172.19.33.32:80 from your App instance - failed, internal error. Please retry. Please submit a feedback if error persists. TCP ping to 172.19.33.32 failed, error code:undefined

I continue to get this error despite multiple troubleshooting efforts.

App Service is part of a App-VNET which is Peered with another VNET that connects to customer networks.

Four months ago we could TCPPING the address above successfully.

Azure Virtual Network
Azure Virtual Network
An Azure networking service that is used to provision private networks and optionally to connect to on-premises datacenters.
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Azure App Service
Azure App Service
Azure App Service is a service used to create and deploy scalable, mission-critical web apps.
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Accepted answer
  1. KapilAnanth-MSFT 41,071 Reputation points Microsoft Employee
    2024-06-12T05:21:49.3266667+00:00

    @Peter Mello ,

    Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.

    "172.19.33.32" is not an "external IP" , i.e., not a Public one

    Can you provide more information on this IP?

    • Where exactly does this IP exist?
    • Is it associated to a VM in the same VNET or the Peered VNET
      OR
      A server from OnPremises connected to Azure by VPN or ExpressRoute?
    • There is a high chance that the IP "172.19.33.32" is not listening in Port 80 to begin with
      • How are you confirming that the IP 172.19.33.32 is "still" listening on 80?
      • You can use a VM in the same VNET as the AppService and telnet to 172.19.33.32:80 and test this
    • If possible, please share a network diagram between your App VNET and the destination "172.19.33.32"

    Cheers,

    Kapil

    2 people found this answer helpful.

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