I am making PCB with RP2040 and W5500. I am looking these schematics. first , second. In this designs,the first is using gnd and cgnd.The second is using agnd. I know the digital gnd is much more noiser that analog agnd. In real design (i couldn't do it yet) which one should I fallow ? For example I am using W5500 for http request. If I use gnd will it increase my wait time? I am wondering if I use agnd, can my http request faster? I wanted to ask because I have no experience with either.
My second question is when I looking for designs I saw cgnd is connecting to agnd's polygon. Why are we using cgnd then?
Can I use GND instead of CGND for this photo?