Regarding rock-ons, if you installed the most recent testing version, you may suffer from the following bug introduced by yours truly (apologies):
As for the “shell in a box”, this is a pretty recent addition and it doesn’t work for me either at the moment (although not with a 502 error). It has some settings you can change under System > Services, but I’m just using ssh for now.
NFS is supposed to just work though, so perhaps there are some clues in the dmesg logs?