with the newest firmware (5.00n and higher) and the new ProfiLuxControl (5.0.0.11 and higher) we were able to increase the speed and reliability in most cases - but in some cases this produced problems in some environments

I think the reason is that some PCs have problems with the high speed connection - but there is a simple solution:
It is possible to activate a delay in ProfiLuxControl:
Edit the connection settings -> set the checkmark "RS485 delay"

RS485-Delay.jpg

this should be done only if there are connection problems - otherwise it should left unchecked in order to obtain the maximum connection speed