Getting connection timed out with traffic manager DNS and app gateway public ip

@Ankit saini .

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

connection timed out error are mostly associated with TCP session is not getting established.

If you application gateway health probe to backend container app is showing healthy that means you backend connectivity to the container app is fine. However, the connectivity from your test machine to application gateway front end ip is getting blocked somewhere.

i have added gateway public ip as external endpoint and status for this endpoint showing online in traffic manager.

Kindly note even though you have added the application gateway public ip as external endpoint on traffic manager, the TCP connection from your test machine is directly formed on application gateway public front end ip address as traffic manager just provide DNS based load balancing and actual TCP traffic does not pass through it rather TCP traffic directly formed between client test machine and application gateway public ip.

Kindly check for below causes -

1. Check if the TCP session between your test machine ip and application gateway frontend ip address is forming. Run the below powershell command in your Machine (WIndows)

      Test-NetConnection -ComputerName <application gateway public-ip> -Port <application port>
   

2. However, your machine is Linux run below command

      nc -vnz <application gateway public-ip> <port-no>
   

3. Check the certificate presented by application gateway is valid or not id you are using https. you test machine should have openssl installed for below test -

      openssl s_client -connect <FQDN_or_IP>:443 -servername <FQDN> -showcerts
   

4. Check the NSG enforced on the application gateway subnet if your test machine public ip address is allowed in the inbound rules of the NSG enforced on the application gateway subnet.
5. If the internet traffic passes through any firewall either on-prem (if you are testing from on-prem location) or on Azure. Ensure that you have right rule allowed to pass the traffic.
6. Check the end-to-end routing from you test machine to application gateway public ip.

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Thanks,

Ujjawal Tyagi