Here is a menu 24.8 session, typing "ip adj wanif0" will tell you current MSS on WAN:
314> 314> ip adj wanif0 adjust TCP mss on wanif0 to 1400 314> 314> ip adj wanif0 1452 adjust TCP mss on wanif0 to 1452 314> 314> ip adj wanif0 adjust TCP mss on wanif0 to 1452 314>
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