Oh, my! That brings back some fuzzy memories...
As I remember Arachne, my opinion was that it "tried too hard to look like Windows". I've just downloaded the latest version, and will attempt to install it "when the spirit moves me". (waste of time trying it in dosemu, I suspect)
I also remember "Nettamer"... I don't think either of 'em had source code.
As I recall, the stuff from Waterloo University *did* have source code - in C, and pretty cryptic, but source code! Seems to me I managed to paste together a couple of those apps, via a batch file, into a crude mail/ftp "client".
Then Win95 came along... I think 3.11 - "Windows for Workgroups" - had the mysterious "winsock" that we need, too... and that was *so* much easier than wrestling with dos that I caved in. :(
So I never really learned what this stuff "is", at a low level. Very seductive to just socket/connect/bind/send/recv, and let "others" worry about the complicated parts. I don't know if I've got the ambition to go another round, or not. It would be "satisfying" to really grasp what's going on at a low level... even to "write your own driver", perhaps... Not the easiest way to get connected, though!
I'll be interested to "follow along" with anything you discover, in any case!
Best,
Frank