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I cannot connect to my backend server which is azure VM (ubuntu 20.04 server). I've attached error detail and my NSG. I've tried most of the troubleshoot documents from microsoft.
Cannot connect to backend server. Check whether any NSG/UDR/Firewall is blocking access to the server. Check if application is running on correct port. To learn more visit - https://aka.ms/servernotreachable.
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Any luck looking at the back-end server itself as mentioned before?
Make sure that port 80 has the service running and the local firewall has it open.
The gateway back-end settings host name override suggests there is an custom domain name for the http website uRL, is this correct?
Is there any way I can remove public ip for my VM and connect only via gateway?
Yes, that's the way you should be deploying the VMs (Depending on how you deploy VMs.)
If you need to connect, you should either use a jumphost/VDI (assuming you have Remote access to it) or Bastion.
Here are all of my settings for the gateway.
And this is backend health with detail.
I made some changes and it was working fine so i deleted public ip from my VM. Now i get this error: Received invalid status code: 502 in the backend server’s HTTP response. As per the health probe configuration, 200-399 is the acceptable status code. Either modify probe...
The gateway back-end settings host name override suggests there is an custom domain name for the http website uRL, is this correct?
No there is not.
Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.
I understand that you are facing issues configuring a Linux server behind App gateway
I see you have done a lot of troubleshooting and the recent issue is that you are receiving the error message, "Received invalid status code: 502 in the backend server’s HTTP response. As per the health probe configuration, 200-399 is the acceptable status code.".
Cheers,
Kapil
May I know if you got a chance to review my previous comment?
Kindly share the backend health details to further troubleshoot this issue
Thanks,
Kapil
Sorry can't see the error details, but have you checked the ubuntu firewall (ufw) whether the required communication is allowed ? Any other VM in the same subnet can access the Ubuntu on the same ports (as the gateway is trying to reach) ?
I just added http comunitacion to the firewall on ubuntu, still same problem. There is only one VM in subnet
Hi, Can you check if you have specified the right IP address in the backend pool of Application gateway? Also check if your service is running on port 80 and it is accessible locally. Then you can check your ip tables whether the traffic is allowed or not.