Next time (if there is next time) don't post screenshots, because they don't show everything. It's better to post text export. You can get it from terminal, if you run e.g. "/ip firewall filter export" for just firewall filter, or "/export hide-sensitive file=somename" for whole thing and it will be saved as somename.rsc. But in this case, if it's default config and you didn't change the rules, it's ok.
But on topic, my suggestion is to do one small modification. Default firewall blocks new connections from WAN (rule #11) and allows everything else. I find it better to list what should be allowed and block everything else, which in this case can be accomplished by adding two rules at the end:
/ip firewall filter
add chain=forward in-interface-list=LAN out-interface-list=WAN action=accept comment="allow access from LAN to internet"
add chain=forward action=drop comment="block everything else"
Then you can disable #11. And you don't need to worry anymore about blocking your separate interface, because it's automatic. If you want to enable something else, e.g. access from that interface to internet, simply add another rule before the last blocking one:
/ip firewall filter
add chain=forward in-interface=etherX out-interface-list=WAN action=accept comment="allow access from etherX to internet"
Also check if you have interface lists configured correctly. Default ones are LAN and WAN, but you can add a new one for your port, if you want. It doesn't change how it works, but can be simpler to manage, if you use same interface in multiple rules.