From what you say, I think it has nothing to do with the server, it occurs to me that it is something in your startup script, the command line probably cuts off when it reaches a certain character limit. You should try loading the mods from a list external to the script, there are some scripts on the internet that show how to do it.
There is also a tool called server manager to directly do everything from there.
https://github.com/mr-guard/dayz-server-manager
Greetings!