That seems like a pretty aggressive security on their part. The server/client does broadcast/listen on UDP port 2999 to look for any other running servers of Eco, but this is fairly standard discovery practice.
Is that restriction on all port ranges? Eco does default to a pretty low port number which some security programs do not like.
Either way there is no way at the moment to change/disable the LAN scan at the moment, but we can add support for it if you want to create a bug about this issue.