I could not add another vnet to my vm, nor change assigned vnet to another. Found in a documentation:
If you create a VM and later want to migrate it into a virtual network, it is not a simple configuration change. You have to redeploy the VM into the virtual network. The easiest way to do this is to delete the VM, but not any disks attached to it, and then re-create the VM using the original disks in the virtual network
That's strange. Why i can not attach my VM to a different network ? I could do it on any hypervisor.
Interface flap for OS causes DHCP process to jump in to get the right ip.