Time Machine - Troubleshooting
C16. The network backup disk does not support ... AFP features
Time Machine - Troubleshooting
C16. The network backup disk does not support ... AFP features
Either of these messages means your 3rd-party NAS does not support the version of OSX your Mac is running.
Some popular makers' information about this on Lion:
LaCie NAS (scroll down to that in the link). May not work on Lion.
Also see: OS X Lion: Connecting to legacy AFP services.
This is one of the risks to using a 3rd-party NAS. See the pink box in Time Machine FAQ #2.
If these are your only backups, see Time Machine FAQ #27 for some suggestions.