I've done a factory reset of my 2860n in an attempt to solve another problem. I use a long MAC address whitelist to control WiFi access, which I had carefully backed up before doing the factory reset.
But I can't get it to restore.

I go Wireless LAN/Access Control and then Browse to the backup file and click Restore.
After several seconds, it says the list has been restored... but the list remains empty.

I have a vague recollection that you need to actually tick Enable MAC Address Filter for the desired SSIDs *before* doing a restore, or it doesn't work. Done that.
I also vaguely recall that you must leave the filename (wlacl_[date].cfg) unchanged, or the restore fails. Done that.
But it still doesn't restore.

What am I missing?

TIA

Mark