I am not a networking professional and I am open to any criticism on how to implement it in a better way.
Official wiki page by Mikrotik regarding Hairpin NAT: https://wiki.mikrotik.com/wiki/Hairpin_NAT
Step 1 - add LANs to "address-list"
List all your LANs like this:
/ip firewall address-list add address=192.168.10.0/24 comment=Management list=LANs /ip firewall address-list add address=192.168.11.0/24 comment=Work list=LANs /ip firewall address-list add address=192.168.12.0/24 comment=Security list=LANs /ip firewall address-list add address=192.168.13.0/24 comment=Home list=LANs /ip firewall address-list add address=192.168.14.0/24 comment=Guest list=LANs
Step 2 - add WANs to "address-list"
If you have a single dynamic IP - add your "/ip cloud" domain to address-list named "WANs" and Mikrotik will automatically resolve it to IP. Using custom script in "/ip dhcp-client" is another option in order to keep WAN IP address in address-list updated.
If you have multiple WANs - it gets a little more complicated. I've written a simple solution for multiple dynamic WANs here: viewtopic.php?f=9&t=171049#p836067
List all your WANs like this:
/ip firewall address-list add address=188.8.131.52 list=WANs
Step 3 - mark connections from LANs to WANs
Use this rule:
/ip firewall mangle add action=mark-connection chain=prerouting comment="Mark connections for hairpin NAT" dst-address-list=WANs new-connection-mark="Hairpin NAT" passthrough=yes src-address-list=LANs
Step 4 - perform Hairpin NAT
Use this rule, placed before any other NAT rule:
/ip firewall nat add action=masquerade chain=srcnat comment="Hairpin NAT" connection-mark="Hairpin NAT" place-before=0
Step 5 - port forwarding
Setup port-forwarding like this:
/ip firewall nat add action=dst-nat chain=dstnat comment="Port forward: something1" dst-address-list=WANs dst-port=5001 protocol=tcp to-addresses=192.168.0.8 to-ports=5001 /ip firewall nat add action=dst-nat chain=dstnat comment="Port forward: something2" dst-address-list=WANs dst-port=5002 protocol=tcp to-addresses=192.168.0.9 to-ports=5002