I have the same HW same problem now. I have tried the firmwares as follows:
wl-500v2 1.9.2.7-7f
wl-500v2 1.9.2.7-7e
wl-500v2 1.9.2.7-7b
wl-500v2 1.9.2.7-6b
wl-500v2 1.9.2.7-6a

but the...