To be honest, the documentation for our router isn't the best, but with a mix of downloaded PDFs, information from the router FAQs written by the UK distributor, and posts by users on the distributor's forum, I managed to get everything set up. The new IP addresses were added to the router's IP alias table, and set up so they weren't part of the default IP pool for out-going NAT addresses. I then set up a couple of test services using the router's multi-NAT functions, specifying specific IP addresses for each server's remote desktop and installing a RDP client on my iPhone.
But I couldn't connect to any of the new IP addresses. The old one was working just fine, but nothing was getting through.
I was stuck, even though it seemed I'd done everything correctly. I checked with a friend with the same set up, but he couldn't connect to my servers either. So, I documented everything, and sent it back up to my ISP.
Just before midnight last night I got an email from them (midnight, on a Sunday?!), saying they'd restarted my DSL service from their end, freeing up a routing configuration that hadn't propagated through their systems correctly. I fired up the iPhone, and connected to both of the new server RDP connections, and to the temporary web server I'd set up. Our new addresses were online and routing correctly.
It's a good feeling when something you've been puzzling over for a couple of days suddenly comes together, and you realise you'd got it right all along.
The next task is to move the router to the first socket in the house to get rid of the ATM CRC errors, and to hopefully eke out a megabit or so more bandwidth. That and to finish the Exchange migration, upgrade the main server to Windows Server 2008 R2, and move our BES from its server onto a VM on the new quad-core machine.
Once a sysadmin, always a sysadmin.