I try to use this rule, but not work.
add chain=input protocol=tcp action=accept src-mac-address=xxxxx in-interface=WAN
add chain=input protocol=tcp action=accept src-mac-address=xxxxx in-interface=WAN
add chain=input action=accept in-interface=wan_iface src-address=remote_ip protocol=tcp dst-port=80
Move in over your drop rule in input chain. Is risky if you not specify src-address!