When MTU changed, system panic occured

Hello
I have some hpux 11.23/31 systems ,and some other (linux,solaris)
I know if i want change the mtu size ,need use lanadmin.
But:if i try on 11.23 : ifconfig lan1 mtu 8000,system paniced.
If i try on 11.31 :ifconfig lan1 mtu 8000,remove ip address from interface.

Ithink is not a best solution .
a

I doubt that the drivers can handle an mtu of 8000. That's rather large.