your case is ENOTSOCK. which means the file description it’s not a socket.
a probably reason of this error happens is because the socket is closed for some reason and the file description is reassigned to another operation which is not socket. So, for some reason, the socket is closed but FSocketMac is not destroyed. and the net drive keep using the old FSocketMac to connect the new session.
which unreal engine version are you using? which platform is it?
if you want to debug this issue, you can also print stack trace dump in FSocketMac::Close function and FSocketMac’s construction. there must be some where called socket close function but didn’t destroy connection in engine source.