How to fix website access in different internet connectivity?

Question

Hello Team,

Good day.

We given with SFTP hosted in public server, the sftp site is accessible in one of the internet connectivity but was failed to connect from another internet connectivity on same machine.
I would like to understand , how we can identify the root cause and how can fix this issue. Please help me on this.

I faced this problem in azure virtual machine.

One of the virtual machine, i was able to access but another one i couldn't.

Thanks,