The support, which stood ready at least in English, told me that I should perform a firmware upgrade. On the side of TRENDnet I loaded the latest firmware and wanted to play this well, but the router constantly reported "Invalid Firmware Upgrade. Must reboot now" and even though I selected the correct firmware. After so I put some time in searching, I realized that I'm not the only one with the problem described.
My guess: Either there is a faulty margin or only my router was / is defective. Thus, I give only 2 stars, because after all, the data throughput unlike other routers was high and there was also a good Wi-Fi coverage.