Problem C8000v shows first interface as GigaitEthernet5

Problem is seen when a node is rebooted such CSR 1000v or C8000v
They loose original interface numbering such as GigabitEthernet1 , 2 , 3 , 4
becomes GigabitEthernet5 , 6 , 7 , 8

and interfaces do not come back because saved configuration inside IOS is for interfaces GigabitEthernet1 or GigabitEthernet2 etc in the running config

Fix is to absolute MAC Address value with starting MAC for 1st router as

50:00:00:01:00:00 for route 1
and then
50:00:00:02:00:00 for router 2 and so on

After fixing the MAC-address problem in PNETLab view the internal platform hardware allocation

write memory
show platform software vnic-if interface-mapping

! clear platform software vnic-if nvtable
! reload

The nvtable command clears CSR1000v’s persistent vNIC/interface database. After reboot, the stable adapters should be mapped again starting from GigabitEthernet1. Cisco documents this exact procedure for resetting mismatched vNIC mappings.

show ip interface brief
show platform software vnic-if interface-mapping