Please see my old post here:
https://community.sophos.com/products/unified-threat-management/astaroorg/f/60/t/56624
Very strange issue.
Finally, I changed the trunk speed to 100M, everything works!
Don't know is the hardware issue or software issue as I have some AP50 working under auto default.
It is very very uncommon that need to change the trunk speed!
Switch: CISCO ws-c3750 IOS 12.2
version: 9.315-2
AP50 version: v1
This thread was automatically locked due to age.