You cannot bridge PPPoE to another interface as the client-server connection is IP / layer 3, not ethernet / layer 2.
To communicate with Router1 your PPPoE server ether1 requires an IP address, and you can use proxy ARP so the Mikrotik answers ARP requests for any PPPoE client addresses overlapping with the 192.168.0.0/24 subnet.
Thank you, proxy-arp was the solution.
My config now looks like the following:
/interface ethernet
set [ find default-name=ether3 ] arp=proxy-arp
/interface wireless security-profiles
set [ find default=yes ] supplicant-identity=MikroTik
/port
set 0 name=serial0
/ppp profile
add bridge-learning=no dns-server=8.8.8.8 name=TestProfile1 use-compression=no use-encryption=no use-ipv6=no use-mpls=no use-upnp=no
/interface pppoe-server server
add authentication=mschap2 default-profile=TestProfile1 disabled=no interface=ether2 service-name=PPPServer
/ip address
add address=80.80.80.249/28 interface=ether3 network=80.80.80.240
/ip route
add disabled=no distance=1 dst-address=0.0.0.0/0 gateway=80.80.80.41 pref-src="" routing-table=main scope=30 suppress-hw-offload=no target-scope=10
/ppp secret
add local-address=80.80.80.249 name=User1 profile=TestProfile1 remote-address=80.80.80.246 service=pppoe
Encryption really slows down the hEX S. Any recommendation in tuning the configuration?
I am not sure what to set at "local-address" in "/ppp secret", but it is working. I am insecure, because it is the same ip at ether3.