Mikrotik 2011 is connected to internet thought FritzBox 7590, internet speed is 40mbs but in FritzBox (provider dsl router) is 250mbs.
What should I check?
FastTrack in Filter rules & Fast Forward in Bridge is ONwithout knowing much from your config, fasttrack rule in ip/firewall helps on this model. enable it. i have the same router with 100/10 mbps internet speed and works fine..
The router was already with a fast path.Fastpath will help a LOT but I doubt that a RB2011 will be able to do NAT at 250 mbps..
After 125-150 mbps depending on the router's configuration, it simply didn't have enough power to do the job..