It's good you have worked it out.
There's something I'd like to ask - what exactly does it mean 5.1 wouldn't allow you to select the datastore to continue? If it did in 5.0 then it's a regression and it would be nice to fix it. Unless it was a side effect of the network issue. By the way, did you still get the network error after fixing the DNS table with 5.0? (or you have already switched to 4.3)
Thanks