Your weak layer adhesion is caused by not enough flushing between the support filament and the regular model. I’ve had this happen many times, these are dissimilar plastics that do not stick together. If even a little bit of the support plastic is mixed into the model plastic layers will delaminate. Up your flushing.
Also, you didn’t ask about this, but make sure you set your Z interface distance to zero. When you are using support material, the whole reason is to have a clean under side and so there should be no space between the layers.
Enjoy 