There has been a firmware update issued. When you first pick one up it will have firmware version 4.1.4.1 loaded. Within about 4 to 5 days, version 4.2.4.3 will be uploaded to it. Once that is done, run a factory reset on it. The biggest problem is direct connections with a 10/100 Mb/s device. If you have a gigabit port equiped router, firewall, or switch that can act as an intermediary device between the CGN3 and and 10/100 Mb/s devices that you want to use, you shouldn't have any issues with download / upload speeds. As usual, your own router will have much better functionality when compared to the CGN3.
If you have problems there are people here who can help. Usually running in Bridge mode and using your own router will solve many issues.