In the past week I noticed the planet atmosphere damage is random.
I get the damage even after the first fight and sometimes I get no damage even after 3 fights.
Is this how it is supposed to be?

How do you mean after a fight?

Atmosphere damage occurs when you are out of your ship/vehicle on a planet that has a hostile atmosphere not on what you are doing on that planet.

The new server seems to have a different re-set time so previously if you were outside your ship at 17:00 then you lose HP due to atmosphere damage whereas now it is a different time, not sure what time tho maybe 23:00. Possibly someone else can clarify.

It's 2300 now... and it's not related to the combat you do but the planet you are on

I'm on the same planet and sometimes the damage occurs after 30 minutes of sitting outside the ship and sometimes it occurs after 2 hours.
That's what puzzles me: the randomness.

http://www.swcombine.com/rules/?Environments

It happens every 24 hours at 2300 Combine Time (or 1700 before the time change), so yeah it can be random for you as in when you leave the ship and how long you are outside

So what Naomi is saying is that if you leave your ship at 22:30 Combine time you will suffer damage in 30 mins... if you leave your ship at 18:00 combine time and stay outside, you will suffer damage in 5 hours.

If you leave your ship at 18:00 you are safe until 22:59 and will suffer no damage if you hop back onto your ship before it hits 23:00

I understand now.
Thank you all for the help!

Glad to help Scott :)

I could be wrong, but at one point leaving the ship would always give you environmental damage to ensure people didnt skip the daily damage by boarding an emtity. Are you ever hopping off and on the ship?

Yes, I am hopping. I have to move around when the creatures move or when I'm done with a group.
Certain thing is that at 23:00 I get the message with the atmosphere damage. I'll test and see if I can avoid the damage by being inside the ship at that time.
It would be annoying to get the damage while you are inside the ship at 23:00.

Well it has been a while since I was on a planet with hostile atmosphere, but iirc I never received damage if I was back on the ship by the server reset time, no matter how long I had been off the ship hunting prior to that.

5 Year 17 Day 21, 23:00 Your character lost 10 HPs (5%) (Planet Atmosphere Damage)
17 Year 17 Day 20, 23:00 Your character lost 10 HPs (5%) (Planet Atmosphere Damage)
27 Year 17 Day 19, 23:00 Your character lost 10 HPs (5%) (Planet Atmosphere Damage)

23:00 every day.

I build for a living and I never got damage for leaving my ship and I have done it up to 80 some times a day without any special suit to protect me. Environmental damage only happens once a day right now.

If you are building, then you are in a city and atmo damage doesn't occur in a city - only on terrain squares.