WAP4410N Strong Signal, but Poor Throughput

[fpcflexible]

I have several WAP4410N access points distributed through our plant and office.  One recently started giving trouble:  the signal is strong, but the data transmission is terrible.  I'm getting slow data transmission and high packet loss when I connect to it via its wifi signal.  If I connect to it via a different WAP (through its wired port) it works perfectly.  The problem unit is mounted near the ceiling and nothing has moved to change potential interference.

I have tried:

• different channels
• firmware update
• rebooting the unit

The firmware update may have made a slight improvement, but not enough.  Any other suggestions, or is this unit toast?

[fpcflexible]

Well, some combination of physical relocation, drawing power from a different circuit, and increasing the channel separation from adjacent APs resolved the problem.  My best guess is that some nearby electrical device is malfunctioning, causing RF interference.  We never found the actual cause of the problem, but the unit is functioning well again.