Not quite reach advertised Technick

Well the FritzBox 7490 works, but in WLAN AC mode only very slowly - more slowly than in the n mode and contact with such devices will not work until the 2nd or 3rd start, which is very strange. Also allegedly be two USB 3.0 ports. In the default mode, a Green USB 3.0 hard drive transmits only 2.5-3 Mbits / sec. if it is FAT32 - NTFS in even less than 2Mbits / sec.
After conversion in expert mode in the power mode, however, the transfer rate for the FAT32 disk rose to 10-12 Mbits / sec and the NTFS disk only 5-7 Mbits / sec .. I close both panels directly to the Computer to USB 3.0 on both boards achieve transfer rates of about 80-120 Mbits / sec. My old telecom Speedport 920V Box was there in USB 2.0 mode clearly better!
But perhaps there be achieved in more recent firmware updates even more ???