To port forward with RouterOS, you need allow the port through the firewall, *and* actually forward traffic
# Allow through the firewall
1. Navigate to IP > Firewall from the sidebar, then go to the Filter Rules tab from the top
2. Select Add new
3. Set `Dst. Address` to the internal IP you want to allow traffic to
4. Set `Protocol` to `6 (tcp)`
5. Set `Dst. Port` to the port you want to allow traffic through
6. Set `In. Interface List` to `all` (I'm sure this isn't the most correct option), but it works
7. Set `Action` to `accept`
8. (Optionally) add a comment explaining what you're doing
# Forward traffic
1. Navigate to IP > Firewall  from the sidebar, then go to the FilteNAT, select `Add New`
2. Set `Chain` to `dstnat`, set `Protocol` to `6 (tcp)`
3. Set `Dst. Port` to the port you want to forward
4. Set `In. Interface List` to `WAN`
5. Set `Action` to `dst-nat`
6. Set `To Addresses` to the internal IP you want the traffic to go to
7. (Optionally) add a comment explaining what you're doing