I have one strange problem with my RB951Ui-2NhD router on wireless. I set my PPoe connection, and when im close to router everything its ok, i have great network coverage and internet too. But problem start when i facing away from router (go down on the first floor on my house). There i have 4 bars network coverage, but yellow "!" show me on network, and cannot open nothing. When get my notebook and go close to therouter, i return my internet connection. I forget to tell you i have RouterOS 6.20 on my RB currently. Whats the problem here.?
From your description this does not seem like a wireless problem with your Routerboard but rather with your Netbook. It probably still knows a different network you tried or used in the past and automatically connects to it when you get close. Try and clear this list and also see if that is what is happening.
Did you setup your PPPOE on the routerboard or do you run it on your laptop?
If it connects and works fine when close to the router there is no reason why it wouldn’t when being a little but further away but still with 4 bars.