Different result real time and post processing

Hi all, how are you today.
My second radio has arrived.
Today I try it, this is result:

  1. The real time I got 1.025 km, still fix and stable, I just walk so I didn’t continue my observed. (all time fix)
  2. Back home still fix, but in one segment float (no obstacle, just suddenly drop to float), I just walked, then fix again.
  3. I walk under tree, got float, then walk to full sky view, still float, hard to got fix

all segment fix except, 2 minutes first, suddenly float without obstacles for afew minutes, float under obstacles, more than 90% fix.

After that just now in my office try to post processing, the result is different.
This is my log file.