It was probably my fault in configuration, however the idea was to have a DropBox whereby I could put in files while travelling with my laptop and those files would be taken up with my home server.

Except that it worked in reverse. My laptop was 'emptier' than the home server, so the home server's files were deleted to match the laptop. Hundreds of megabytes of files were destroyed before I managed to stop it.

On top of that, I only had a 2 gig per month quota for internet access while travelling, and all the DropBox activity soon exhausted that in days.

On later trips my own home server coped very well, with less overall unwanted activity.