They should all function perfectly ‘out of the box’ or after doing a factory reset i.e. using the default settings.
If you think you may have altered the default port settings, then there are two things to check.
First, on the Web UI, go to NETWORK > LAN > LAN INTERFACES:lan and click on ‘Edit’. Next, select the ‘Physical Settings’ tab and you settings should be the same as the screen below - eth0
Second, on the Web UI, go to NETWORK > PORTS > PORT SEETTINGS and click on ‘Sellect all’ and then the ‘Edit ports’ button. You will have more ports than my exxample, because I’m taking these screen shots off a RUTX09.
My first idea was that every eth-port have independent addresses as linux-servers, but if bridge is needed with this I can always add seconday addresses to related bridge… in routing perspective its all the same.