so i have the ring of starless skies on just got the grandfather and im trying to equip it and it wont let me but the moment i take the ring off it allows to me to equip it is there a certain req to be able to have more then one mythic equipd at the same time ?

Depends on how you got them, new rule being you can only equip 1 crafted mythic at a time, if you crafted both(with the cube or at the blacksmith/jeweler) that's your problem.

Can only equip one that was crafted

crafted for sure