I could not upgrade license on Server 2012 with DC, DNS, file, print and fax services.
I added Hyper V and created 2012 eval virtual machine on same server and transfer all roles and remove ADDS out of main host and rejoin it to domain.
I had some issues unjoining and joining it back to domain as I used second NIC for virtual switch and IP on both NIC was active, once from physical NIC and one from virtual NIC that was used in guest HV which is DC now.
It finally worked though users had issue getting file and printers, therefore, I had to map all of them manually. I tried easier fix first by adding second A record on DNS for host server using IP of second NIC but that really did not help to map with name, therefore, I used second NIC ip address to map them all back manually.
It could have been better if I had teamed NIC or used the same NIC, but I did not wanted to take a risk on teaming on a DC that was already running with one IP and ended up using second card for HV switch.
Once I apply the license I will put all role back to main server and decommission VM. Is there any advise on NIC situation to avoid same issues when old DC gets decommissioned?