Infill not printing well. What I am doing wrong? I am a new to 3D printing, somehow, the infill of my print compiled by Cura 4.5 is weak. I print with generic PLA (FD plast) on 200 °C. See image below:

Print details: I have a Zonestar Z6FB which I use together with Cura 4.5. I print in PLA at 200 °C (Cura default for PLA). The print bed is set to 60 °C. I use a print cooling fan at 100 %. The layer height I set to 0.1 mm, the line width (wall thikness 0.8 mm?) from the 0.4 mm nozzle. The Printing Speed is set to 60 mm/s for everything. My retraction is unknown.
You problem clearly under extrude which mean the plastic not flow as much as it should be.
I face this problem recently here my step to solve.


Tune e step (do this first)
Add more temp. to nozzle (so plastic will melt and flow faster)
Slow down print speed.
Change nozzle and clean whole hotend.