I get No server message over access point. if I restart the Qlikview server service then it works fine.
This happens very frequently . users have to wait until we restart the Qlikview server service. I am sure it is not recommended to restart the qlikview server service every now and then as we might end up facing lot of issues in future.
The cause is probably any overload on your system. Did you are following the hints from the link above to monitor the resource-consumption? In the first step you may not mandatory need all the log-files else keeping an eye on the taskmanager and the usage (user + documents and/or any parallel running tasks) within the qmc may already hint from where the overload does come from.