I only said it was the most common because that's what I have seen. Either mode should be fine, and neither is 'preferred' over the other.
I think what you might be hitting is a bug, where vCloud assigns the scope starting at 1, when it shouldn't be.
you should be able to stop all cells, then look at the network_pool table in the vCloud Director database. update it to show the correct vdnscope- value (vdnscope-2 in your case), and start vCloud Director again.
After that it should work just fine.