During the Data Protector migration we noticed that the performance on the new Data Protector Cell Manager was a lot lower than the performance on the old solution. Speeds of around 100Mbit was the best we ever could get from it, although the machine is running on a gigabit network.
To make the case even more strange, performance on other network tasks was quite normal where the gigabit connection was maxed ASAP.
After some digging, the problem turned out to be that the server was running the old default drivers for the NIC (Broadcom BCM5708S netXtreme II GigE). Windows update has in the latest Windows versions become better on delivering driver updates but that was not the case this time.
After installing the newest drivers from Broadcom`s website the performance jumped straight to gigabit even on Data Protector.