Methods I have used in the past for this....
This is a bit freehand, and may not work... but the basics is to find the position of the string you want then use that as part of the substring command:
$parameter2 = substring($parameter1,(len(listgetelt(strtolist($parameter1,"net"),1)) + 1)) ;
The other is to use regex:
$parameter2 = listgetelt(match_regex($parameter1,'^net(.*)',''),1);
I personally prefer regex, but note that the more regex you use the more overhead the cell will have.