Sn_SSR is always 0xFFFF

i have problems with wiz830mj. i’m using wiz830mj with renesas R5F56218BDFP MCU(16 bit data bus/direct).
i can set values to SHAR,GWR,SUBR and SIPR. Then wiz830mj responses ping from pc. After set those registers, i can read same values from wiz830mj. But the problem is when i read Sn_SSR it is always 0xffff.

Sn_SSR is 0x0000 after reset.
You maybe use abnormal address of Sn_SSR.
Check again to valid Sn_SSR address definition in your code.
Thank you.