Using WinBox
IP > Address > Add static IP from ISP and assign to the WAN Interface (probably ether1)
IP > DNS > Settings > Add DNS from ISP
This is the bit I spend a while trying to acheive…
IP > Route > Add 0.0.0.0/0 and Gateway IP from ISP
IP > DHCPClient > Dissable/Remove the DHCP client on WAN Interface (Ether1)
Not needed for the above but a tip for the Firewall (how to add an IP rule / 'port forward all ports'):
IP > FW > Filter Rules > + > General > Chain > Input → SrcAdd (IP adress that want want to allow in) > Protocol > 6(TCP)
When the rule is created, MAKE SURE THE RULE IS SHIFTED ABOVE the deny rule