i am actually playing the whole WC series again, 30 years later after first play ;-)
everything was fine but now i reached WC4 and WTF ?

i always played difficult level ace. and WC 1,2,3 everything was fine.
but in WC it is simply impossibe. its not difficult its unfair.

what is wrong with the rockets in this title ?
one hit, instant death.
and whats the problem with the wingman. in almost every mission they give up at first enemy contact.
is this kind of a glitch ?

I just started WC4 up for the first time in yeah....similar to what you wrote...almost 30 years since I last played it and I also noticed how insanely difficult the enemy AI is also. I played just on Veteran (I think) level of difficult that one missile hit = instant death. I really don't remember the game being that difficult when I first played it all those years ago but then again maybe i had turned down the difficulty to Rookie back then.

Kudos to whoever is able to play the game on Ace difficulty. I already got burned retrying the same mission (the rescue the scientist from the planet surface mission) over three or four times - ground SAM launches missiles at me non-stop and one hit means instant kill. I turned on Invulnerability but then that does take away the fun of getting through the missions.

By now you've probably already moved on, but for anyone else who runs into this issue. I do think that there is an issue with the game. The DOS version is no where near as difficult as the Windows version and probably because it runs a bit slower.

For the past 2 days I've been trying to find an answer for why this game feels so insanely difficult. I have a theory that part of the issue is running a game that was designed for Windows 95 & 98 on modern hardware. I locked my FPS to 60 and this seemed to fix most of the issues. Without locking the FPS, I was getting really weird game behavior including enemies spamming missiles within 10 seconds of reaching a nav point... wingman dying in all of 5 seconds and wonky hit registration. I mean Wing Commander 4 is challenging, but it shouldn't be THIS challenging. I watched old game footage on YouTube and realized other people weren't running into these issues.

So if you feel like the difficulty in WC4 is a little more over the top than usual, you might try locking your FPS to 60 or 30. I used Rivatuner. After locking my FPS, I was able to get through Tyr (one of the most challenging missions in the entire series) on the first try.