I am upgrading a 2.2 server to 4.1. A large number of people seem to be asking this old question anew. NW 4 and NW 3 and NW 2 bindery services man use VLMs or NETx. ODI is a method of handling the lan adapter itself. Ancient monolithic IPX.COM which included a board driver is many years out of date and should be removed from your site.
NET is also out of date.
NETX is the last of the series and is independent of DOS version. In a very few special cases you may have to use NETX to placate an old application. I think you are operating under a misimpression. VLMs live above 1MB and are brought down below that barrier for execution one by one when needed, overlaying what was there before. They overlay each other.