This night and this morning there has been a hacker active that has done a lot of damage to the SA:MP Main Server List.
If you check you will see that all official servers, and a number of others seem to be down.
We found the same situation twice for our server.
The server itself is running without a problem, but once the main list is hacked it shows a ping of 9999 and connections are lost.
In this case a server restart makes it able to connect again.
This is a problem of the SA:MP team, and until they solve it we can only monitor the server and restart when the same happens again.
Our server has been running stable and without major incidents.