Finally!
After more than one week trying desperately to make my Asus Pundit boot via PXE using a kernel located on a remote server and getting nowhere, or let’s say getting very near, but being barred by
nfs: rpc call returned error 101
error messages and no login, I finally found the solution, thanks to “pizza” who had a similar problem with his soekris box, and who realized at some point that /etc/rcS.d/S40networking actually took the network down before taking it back up again which in this scenario, a client booting via NFS from a remote machine, is fatal. Adding exit; at the top of this file solved the problem. Thanks “pizza” :-). I can go to sleep now.