Firewire ports issue

I have 2 mr816x that i want to link up for 16 channels of tracking. My issue is that the interface only functions when I plug in through the firewire 2 ports. When I plug into the Firewire 1 port the computer doesn’t see the interface at all. And I’m unable to link the units together. Both units react exactly the same, both are using the latest drivers as well.
I’m using a macbook pro 2011
Has anybody come across this weird problem?