Slow internet , 1WAN port with PPoE

Hello,

Im new user of Mikrotik, and I have problem with my RB. I got internet 1G but on Mikrotik 900/300-500 ( must be 900/900)
From ISP I got credintial for PPPoE connection. On the old router TPlink 6000 I got 900/900.
Best result I have in Bridge mode but must be TPlink ( as a router ) front of Mikrotik ( as Switch only )

I have to use Mikrotik as router with a few ports for computer, easy configuration for Master of Mikrotik.

Is anybody there to help me out? Prague, Czech rep.

Thx for your answer