I have a handfull of 450g's in my network, I have a need for MTU of 1522.

on some of my 450g routers, i can set MTU as high as 1524, while on others i can only set it to 1520.
I noticed the ones which let me do 1524 have firmware 5.2 or 5.6, and the others which only allow 1520 have firmware 5.19 (which is newer right?)

did they lower the maximum MTU for some reason?
is there a way to change it?

Thanks,

This article contains the table of max supported MTUs for each board
http://wiki.mikrotik.com/wiki/Manual:Ma ... 2.2FL2_MTU

Some of the chipsets do not support more than 1520.

This article contains the table of max supported MTUs for each board
http://wiki.mikrotik.com/wiki/Manual:Ma ... 2.2FL2_MTU

Some of the chipsets do not support more than 1520.

Thanks for the link

I see the RB450g (as all of my routers are) support only up to 1520.

so why does the older firmware allow me to set them up to 1524? is it a bug in the FW and it won't actually work? or was support for those higher MTU's dropped for some other reason?

Support was dropped because of the issues with 1524 byte packets on those boards.