I don't think you would compromise your privacy by posting the model of the Mikrotik device you are using.
Most (if not all) common SOHO Mikrotik devices (routers and AP's) do have a default configuration with one port (ether1) set as "WAN" and all the rest assembled into a bridge and set as LAN with a firewall between them. ("professional" devices are an exception as they usually come without any configuration)
The port with the additional label "BOOT" is - usually - ether1 and WAN.
You MUST use it for Netinstall.
you MUST NOT use it to connect to the device.
This is point #22 here:
GP & CSA (Good Practice and Common Sense Advice) for Mikrotik devices