Thanks for all the comments.
The server Dreamgrid is on has a fixed ip address, It is in Germany and I access it from England through Windows Remote Desktop Connection. Indeed, the new instance is also on that server, which is why the address is now all numbers instead of a proper DNS name. Loopback is not an issue, since the server is in a data centre.
This instance is using the last backed-up oar that I have. My normal procedure at this point would be to backup everything and reset the computer but I can't because I would lose my RDC and am not convinced that I could get it back without paying the Data centre to do it.
Unfortunately, the oar files are huge - 7.2 GB - and when I try to copy them to my home computer the transfer breaks after about 1.6 GB.
I do regular oar and iar backups (every few days). As luck would have it, I hadn't backed up for about two days during which I had done quite a bit of work on the Northern part of the sim. I had also collected some wonderful things that I can't find now (I can't remember where I got them from), so have had to leave them out.
Thanks again for your help, it is much appreciated. :)