Usb to etherneth - connect to a dsl modem/router - configuration

There is some info here in this post:

I would recommend against connecting Reach directly to a modem. Make sure Reach is behind a firewall (router) as it is not hardened for exposure to the WAN, nor should it have to deal with fending off constant botnet attacks. It’s granted that some modems have built-in firewalls though.

You might know that already, but I’m saying it for everyone that reads this.