Here it is, ur mistake
Think for a moment....
Following your detailes u should have gotten something like that?
[admin@your-router] /ip firewall nat> print
Flags: X - disabled, I - invalid, D - dynamic
0 chain=srcnat action=masquerade out-interface=ether1
Correct me if wrong, but u have set your private network on Ether1
If this is right? My question is : Why did u put interface Ether1 as out-interface?
Now u have two options
1. change the rule to
0 chain=srcnat action=masquerade
out-interface="the interface where u set your pppoe client"
2. change the rule to
0 chain=srcnat action=masquerade
src-address=192.168.0.0/24
1st option -> Mikrotik will translate all the networks that are directly connected
2nd option -> Mikrotik will translate network 192.168.0.0/24 which is actually your private network (between Mk and your PC)