Unable to connect to Azure after upgrading to Standard Load Balancing

Question

Unable to connect to Azure after upgrading to Standard Load Balancing

Charles Wolfersberger 40

I upgraded from basic load balancing to standard load balancing on Azure today. Unfortunately, while Azure reports that the deployment of the standard load balancer resource was successful, our employees can no longer connect to the Company's management software platform sitting on Azure.

I suspect the issue may be that I failed to lock the static IP address for one or more resources. However, the Public IP resource IP address matches the IP address for the Public Load Balancer resource. Unfortunately, I already deleted the basic load-balancing resource.

The issue could be something else - but the only change i made in Azure was replacing the basic load balancing resource with the standard load balancing resource.

Any suggestions?

Mythreya Asnala 0 Reputation points Microsoft External Staff Moderator

2026-07-09T14:26:28.04+00:00

Hello @Charles Wolfersberger ,
Based on the provided information, One common reason for this behavior after migrating from Basic Load Balancer to Standard Load Balancer is NSG configuration.

Standard Load Balancer is secure by default, whereas Basic Load Balancer is open by default. So, when using a Public Standard Load Balancer, inbound traffic must be explicitly allowed through a Network Security Group associated with the backend VM NIC or subnet.

Please verify that the required application port is allowed in the NSG. For example, if the management software is web-based, you may need to allow TCP 443. Also confirm that the backend VMs are added to the backend pool and that the health probes are showing as healthy.

Since the Public IP address still matches the Load Balancer frontend IP, the issue is less likely due to the Public IP and more likely related to NSG rules, health probe status, or load-balancing rule configuration.

If you have any questions and concerns, please let me know.
Mythreya Asnala 0 Reputation points Microsoft External Staff Moderator

2026-07-14T15:30:18.8033333+00:00

Hello @Charles Wolfersberger
I wanted to follow up on our previous conversation and check if you had an opportunity to review the information shared. If you have any questions or concerns please feel free to let me know.

Answer accepted by question author

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Your answer

Mythreya Asnala 0 Reputation points Microsoft External Staff Moderator

2026-07-09T14:26:28.04+00:00

Hello @Charles Wolfersberger ,
Based on the provided information, One common reason for this behavior after migrating from Basic Load Balancer to Standard Load Balancer is NSG configuration.

Standard Load Balancer is secure by default, whereas Basic Load Balancer is open by default. So, when using a Public Standard Load Balancer, inbound traffic must be explicitly allowed through a Network Security Group associated with the backend VM NIC or subnet.

Please verify that the required application port is allowed in the NSG. For example, if the management software is web-based, you may need to allow TCP 443. Also confirm that the backend VMs are added to the backend pool and that the health probes are showing as healthy.

Since the Public IP address still matches the Load Balancer frontend IP, the issue is less likely due to the Public IP and more likely related to NSG rules, health probe status, or load-balancing rule configuration.

If you have any questions and concerns, please let me know.
Mythreya Asnala 0 Reputation points Microsoft External Staff Moderator

2026-07-14T15:30:18.8033333+00:00

Hello @Charles Wolfersberger
I wanted to follow up on our previous conversation and check if you had an opportunity to review the information shared. If you have any questions or concerns please feel free to let me know.

Answer 1

Vinodh247-1375 44,556 Volunteer Moderator

Do you have explicit inbound allow rules (source+port) on the backend subnet/NIC?
Is it healthy on the configured port/path? If probe fails, LB drops all traffic.
Did you configure SNAT (Outbound rules/NAT Gateway/Public IP)? Standard LB does not give default outbound access.

Charles Wolfersberger 40 Reputation points

2026-07-14T19:54:49.9533333+00:00

This was helpful. I was able to resolve the issue.

Answer 2

TP 163.1K Volunteer Moderator

Hi Charles,

Did you allow the required inbound port(s) in the Network Security Group (NSG)? One key difference with Standard Load balancer is it is secure by default, whereas basic is open by default. This means if using Public Standard Load Balancer the traffic needs to be allowed by NSG.

For example, if your management software platform is web based then you would typically need to allow TCP port 443 in the NSG.

Below is screenshot excerpt from documentation comparing Basic vs Standard:

User's image

Please click Accept Answer and upvote if the above was helpful.

Thanks.

-TP

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