I now tested the old version of IQfeed on my 32 bit machine,
and all symbols are updating correctly and i have set my pc clock 10 minutes late.
Quotemanager does not collect RT data wo Plotting is disabled.

Next time i try it with IQfeed 4.9 and collect RT data enabled on the same machine.
If it works i will install IQfeed 4.9 on my 64bit machine and the problem should be fixed.

I am now on the new version of MC.Net and the problem is gone therefore i think it was a conflict between IQfeed 5.0 and MC.NET 8.5 not supporting Microsecond timestamps.