Not to hijack, but I have a ZD3100 and 51 2942 APs...and upgraded to 9.7.
Same symptom, connected clients became disconnected clients. Average 300 users total then averaged 51 or so, a LOT of APs have zero clients...oh the horror.
Case opened, but no joy.
Opened forums, I see this, and I downgrade.
CURRENT STATUS: 20 minutes later, am on 9.6.2.0.13, back to high client count, APs have multiple clients.
Case is still open, although I agree with the consensus that the 2942 can't handle 9.7, so perhaps moot.
Just sharing.