RCM4300 MTU Stuck at 16

>> Good day,
>> I'm hoping that someone could assist me with setting the MTU value for the RCM4300. 
>> On boot-up the interface table reports that "eth MTU 16". 
> 
> Using the ETH_MTU macro has no effect, no matter which value I chose it remains at 16. 
> 
>> I can change the MTU of my RCM4010 to a value of my choice using the ETH_MTU macro. 
> 
>> Both modules are loaded with the same code. 
>> I'm using DC 10.7. 
>> Any idea where I can go and look?
>> 
>> Regards
>> Mike