1. Environment impacts your reception. Tho if you are in general area shouldn't matter that much. Also not knowing exactly where you are flying, the direction you are flying could have interference where earlier when you were getting 1200 there weren't. I would start with optimal condition: Flat ground, no obstacle (building, tree, etc)
4. No idea where it is for P3 Standard. But it should be like P2V+ and P3P and P3A. So inspect the landing skid legs. You should see thin gray wire running alone the legs. Use a tweezer to gently tuck on those gray wire to see if they are secured. In P2V+ they are glue down good, so shouldn't come undone. I imagine it would be the same for P3S.
5. I know this can be done on the P2V+. Should be the same for P3S as these birds are sold world wide in both US and Europe. I imagine the same legal compliance are still there and therefore the switches are still there. Check your manual on how to do this.
7. If you are suddenly consistently getting 600 ft where you were getting 1200 ft, I think the most likely culprit is something got knock lose.
8. Your answer on this is still vague. So instead of having you describe to me what's going on, I'll tell you what to look for here. Your P3S is essentially a P2V+ with some minor upgrades, but majority of the components and technologies are the same. That means your drone operates on 2 frequencies: 2.4 GHz and 5.8 GHz. Your analog video links happens over the 2.4 GHz frequency. And your RC control happens over the 5.8 GHz frequency. That also means you have 2 sets of antennas: One for the 2.4 GHz and one for the 5.8 GHz. Antennas are tune for specific frequencies therefore you need 2 sets.
I asked you if you lose video first or RC first to determine which one of your link is the weaker link so that I can direct you to look for that antenna.
Your 2.4 GHz (VIDEO) link antenna on the bird should be a DIRECTIONAL panel antenna that's BUILD inside the bird. In the P2V+, this is simply "glue" on to the side (right and left) of the bird. I suspect this is the case with P3S as well. So look at the vent on LEFT side and RIGHT side of your drone and see if you see a green square panel that looks like this (picture below).
View attachment 39398
And see if they are lose or if they are flush against the side of the vent. Interestingly enough, given this is a directional antenna, you get better video signal when either side of your bird is pointing directly at you (ie. flying side way toward or away from you).
If your RC signal is the one that's cutting out first (if you see video clear, but nothing you do on the stick makes the bird respond, then you have lost your RC signal first. Otherwise if you simply lose video signal, your RC signal might still be perfectly OK), then you would want to inspect those antenna running down the side of the landing legs. This is your 5.8 GHz antennas. These are Omni directional instead of directional like your video antenna.
9. See my respond above on definitively determining which control you lose first. It's unlikely you lose both at the same time. There are 3 possible scenario:
a. you consistently lose video first.
b. you consistently lose RC first.
c. you sometimes lose RC and sometimes lose video first.
C is the "best" scenario that means both antenna are of about same caliber, but I prefer scenario "b".
