I have a time machine setup where the backup location is on a Synology NAS drive; having recently moved house, and ended up with a different router, I setup the NAS drive again, and it has a different IP address (formerly in the 10.* range, now in the 192.* range).
I couldn't - no matter what I tried - get Time Machine on the iMac to recognise the drive as the existing TM location; despite it showing up as an available disk in TM preferences. In the end, I deleted the old backups (nothing required from them yet, so it won't hurt to start again, I suppose). What I'd like to know, for future reference, is if/how I can get TM to recognise the NAS as the backup location if the IP address changes again. None of the hardware changed, so I can't see why this was an issue.