It won't last long at all being buried, like months, unless you put it in conduit. Like others have said, 300' is going to be your limit. You can always extend that by putting in a small PoE switch at the 250'-300' mark.
You could always put an AP at 300' with a high gain antenna.
Glock 17 Gen 3, Glock 19 Gen 3, Glock 30SF Gen 3, Glock 36, DPMS AR15
When a strong man, fully armed, guards his own house, his possessions are safe. Luke 11:21 NIV