Hello.
Please use English language only when reporting issues into the feedback tracker.
As for your issue.
It is possible the issue is somewhere on your network.
Are you able to test the game on another network so we can confirm or deny that is the case?

I used my phone's data connection on my PlayStation and it worked—I was able to play DayZ properly. So, how can I fix this? What instructions should I give my internet service provider? Since my phone's network is much weaker and slower, it would be great to resolve this issue and play properly using my Wi-Fi.

Hello.
You should contact your ISP and simply mention that you have no issues while using mobile network but cannot connect when using your proper network.

Hello.
I understand. The problem is that I only encounter this error with this specific game; I can play other games online without issues using my Wi-Fi—including Arma Reforger, which is from the same company—so I’m not exactly sure what the issue might be or how to resolve it.

This is irrelevant as every game is built differently and some things that affect one game might not affect others