PPP Interface rx is always 0.
/interface pppoe-client
add name=pppoe-out1 disabled=no
add-default-route=yes default-route-distance=1 use-peer-dns=yes
interface=ether1 max-mru=1492 max-mtu=1492
password=pass user=user
/ip firewall nat
add action=masquerade chain=srcnat out-interface=pppoe-out1
/ip firewall mangle
add action=change-mss chain=forward
new-mss=1452 out-interface=pppoe-out1 passthrough=yes
protocol=tcp tcp-flags=syn tcp-mss=1453-65535
without this mangle PC/Phone in LAN cannot open any http/https website
in 6.4x do not need this mangle