Default [q] sl9003 wifi issue

My fone FW:2.3.6; I9003XXKPR; GINGERBREAD.XWKPK
Everything working well, except this issue:
- When Wifi AP WAP4110 (CISCO) set to wireless network mode N only or B/G/N-Mixed my fone is connected to that wifi but can not get in Internet. Other mode : B-only; G-only; B/G-Mixed, my fone can connect wifi and Internet normally.
Does anyone face this issue ?