I use (and I still to use) Syslog Watcer Pro v2!!!
Put those rules at the end of firewall filter drop on forward rules (if you have any):
lista_ip_clienti = automatic list made by pppoe-server profile on "address list" field
this log only the client traffic, and not all the network traffic.
The first rule log TCP, UDP, ICMP, IGMP etc. new connection,
the second the RELATED connection for the first,
the other rule log the other protocols.
add action=log chain=forward comment="Invio Log connessioni in uscita al Server" connection-state=new src-address-list=lista_ip_clienti
add action=log chain=forward connection-state=related log-prefix=RELATED src-address-list=lista_ip_clienti
add action=log chain=forward comment="Tunnel IPv6 dentro IPv4" protocol=ipv6 src-address-list=lista_ip_clienti
add action=log chain=forward protocol=gre src-address-list=lista_ip_clienti
add action=log chain=forward protocol=ipsec-esp src-address-list=lista_ip_clienti
And configure accordingly system / logging
/system logging action
add bsd-syslog=yes name=LogServerNotice remote=1.1.1.1 syslog-facility=local1 syslog-severity=notice target=remote
add bsd-syslog=yes name=LogServerInfo remote=1.1.1.1 syslog-facility=local1 syslog-severity=info target=remote
/system logging
add action=LogServerNotice topics=pppoe,info,!debug
add action=LogServerInfo topics=firewall,info,!debug
Those rules not only log the firewall, but also the pppoe autentication.
ALL THIS RULE ARE VALID ONLY FOR "PPP" CLIENTS, for HotSpot the method is different...
For HotSpot I suggest you to use "Cloud4Wi"...