I am just being my usual obnoxious self.. righteous.. geek.
But Apple did make a bit of a mess with Lion networking.. and it is just not as solid as with SL. At least at its final revision..
The link between TC and Lion seems to get lost on a daily basis.. you will need to constantly reboot.. there is a major issue with AFP dropping out.. so you keep getting server disconnected messages.. I also get those on SL with 7.6 and later firmware on the TC.. none at all when I go back to 7.5.2. It seems also TM has issues if there are other users on the network also backing up.. people are getting issues where they cannot open the sparsebundle.
I am also escapee from windows.. and what I was trying to escape was crummy networking.. so diving into Lion issues... no thankyou.
A few things I picked up.
Use ethernet not wireless if at all possible.. much worse on wifi links.
Rename to the TC to SMB.. the irony of it.. ie windows networking.. Use short names no spaces no special characters.. Apple defaults to names which seem over complex and not conforming to the SMB world but since AFP also has trouble.. better to apply those rules.. so
TC name.. TCGen4 Or TCKelley.. great.. Kelley's TC breaks all the rules.
Wireless name.. TC24ghz.. and separate name for 5ghz.. TC5ghz.. not TC 2.4ghz.. wrong
Passwords can be 8-12 characters.. pure alphanumeric.. no spaces no special characters.
This won't cure it but it seems to help.
Lock the channel for wireless. also helps.