@finau It will "work" but sketchy security wise. You need to read up at link above about authentication. Your command likely needs to include something like this:mongodump ........... --authenticationDatabase=admin
See if you get prompted for pass. Can also include pass on cli via -p flag.
Have fun! o/
Update: Apologies, missed this bit:
Anyway how do you restore that copy on the new fresh forum? Should I just copy it ? if so, where ? (sorry but docs are very slim)