That 2nd link Jorpho posted goes into a bit more detail on how it isn't a pure dos setup (the fact you haven't loaded a driver, it pulls info from system.dat) It may work but I don't trust it.
I'm not a fan of restart in dos mode. I prefer a shortcut to command.com and having full control over what's loaded via autoexec/config.sys files manually so If I really wanted dos networking I would do it this way and use the dos client.
But as you already have Win98 installed I'd just use that for filesharing. Even on my 6.22 PC I only load the 3 drivers required for gaming, Filesharing I do from WFW as mapping drives is the only way to browse a network in dos.
If your doing this simply for the challenge fair enough. sounds like the workstation service is hanging for whatever reason. My 1st guess (and it is just a guess) is maybe the NIC is been assigned different resources in dos mode, run the Netgear diag tool and confirm its resources match up with what device manger has.