ERR_CONNECTION_TIMED_OUT after upgrade from a basic public to standard public load balancer

Question

I've deployed a simple set up using this (https://learn.microsoft.com/en-us/azure/virtual-machines/windows/tutorial-load-balancer). The set up includes three VMs with IIS installed and placed behind a basic load balancer. The site is accessible via LB frontent IP.

Then, I followed this guide(https://learn.microsoft.com/en-us/azure/virtual-machines/windows/tutorial-load-balancer) to upgrade SKU from Basic to Standard LB. The migration looks successfull with the pools, rules, and health probe configured. However, the site is inaccessible from the Standard LB frontend IP and returns "ERR_CONNECTION_TIMED_OUT".) to upgrade SKU from Basic to Standard LB. The migration looks successfull with the pools, rules, and health probe configured. However, the site is inaccessible from the Standard LB frontend IP and returns "ERR_CONNECTION_TIMED_OUT".

Answer 1

Hi, One reason that I can think of is that if you don't have any NSG associated to the backend pool VM it works fine with Basic LB. But for the standard LB NSG is Mandatory and you will need to whitelist port 80 explicitly.