Below might be reason for your problem
/tool mac-server mac-winbox set [ find default=yes ] disabled=yes
That's for accessing Winbox via MAC address rather than IP.
His first allow rule using port 8291 is for a TCP connection as an IP connection.
If you see the proper PUBLIC IP on the WAN INTERFACE in
/ip address
Then as stated by others... 8291 might be blocked by the ISP.
Sometimes the ISP uses Mikrotik and when i try to reach a router... I hit the ISP router instead of my intended unit.
ONCE AGAIN.
If you do have the public IP on you router's wan interface... you could always change the service port that Winbox runs on. Then change you accept rule.
/ip service
set winbox port=8292
/ip firewall filter
add action=accept chain=input dst-port=8292 protocol=tcp place-before=1