Infill Quality - Low

Hi, hopefully someone will be able to give some advice on this.

I am playing around with settings in Cura, trying to get the best quality print. Up until yesterday, I was only familiar with Slic3r (but it was causing me issues). So far, everything is going better with each attempt. One thing that has remained the same is the infill. I raised the infill density from 10% to 20%, and I tried fiddling with some speed and thickness settings. My next attempt has the infill changed from grid to triangles.

What's happening is I end up with a very broken infill. The lines are often incomplete and rough looking, they don't connect in many places. Lucky for me the model I'm printing is only for display, but I'm curious if there's a way I can produce better results? The part ends up being extremely brittle and easy to break/separate. I have attached pics for your viewing pleasure. Thanks!