I am connecting an a mikrotik router (I) through wireless pppoe to another mikrotik router (II).The router II is connected to internet.
I connect my computer to the client (I) router.
If the internet site which I am searching is PINGable, all is ok, but if the site is not PINGable (like http://www.microsoft.com ), I cant get anything. I dont know, what is the reason. . . . 
Hi,
yes, you can not pinging or traceroute to microsoft dot com, you can try to other internet host.
regards,
BalimoreDOTcom
Yes, I know it, it is not a question…I dont want to ping anything, I cant GET theese sites wich the router not pings.
So I can`t see the neither the microsoft site (for example) too.
sorry man
i thing is possible, you can check, for default DNS for your router and make sure you has NAT[masquerade] for that IP or Range IPs to supply them.
regards
BalimoreDOTcom
The dns is ok.
It seems, that it wants to load the microsoft`s site, but it not cames.
The NAT is made for all (0.0.0.0) ip addresses, so it has no difference between one and the other. The only difference is that the site which I can ping, it loads normally, what I can nost ping, It not arrives (but it writes, that the DNS has resolved it)
tcp mss
Exact problem here. See http://forum.mikrotik.com/t/dynamic-tcp-mss-rule-breaks-stuff/8009/1
You need a working TCP MSS rule
Thank YOU very much for help. 
Now the problem is solved!
Now the system works expertly!