Overwrite $SERVER["socket"] from include in lighthttpd.conf

Can anyone tell me how I can overwrite the values of $SERVER[“socket”] which are set in the 90-turris-root.conf file. I would like to put it in lighthttpd.conf after the include directives to be port 81.

I usually edited the file 90-turris-root.conf and did overwrite the values but that is reset on every upgrade. So can anyone please help me out here where and what to place to overwrite jport 80 from 90-turris-root.conf with port 81?

I already tried after the include directive to overwrite with:

$SERVER["socket"] == "*:81"    {  }
$SERVER["socket"] == "[::]:81" {  }

and
$

SERVER["socket"] := "*:81"    {  }
$SERVER["socket"] == "[::]:81" {  }

and

server.socket := ""
$SERVER["socket"] == "*:81"    {  }
$SERVER["socket"] == "[::]:81" {  }

But nothing helps any help would be greatly appreciated