I upgraded the R3 firmware and performed another factory reset, but I'm still not getting any internet connection. I can connect to the router without any issues. The power light, 2.4GHz light, and 5GHz light are on, and the port 4 light is flashing. However, the internet light is off, and the setup process doesn't detect an internet connection. Additionally, the lights on the back of the modem are flashing. I've tested all of the cables and the internet is working fine with the AC5300. Any other ideas?