ROG MAXIMUS VIII FORMULA - Network

[iCeD00D]

Good morning. Strange thing happened to me last night. For months now, I've been using Comcast - cable for internet, until a co-worker convinced me to go AT&T fiber. All went well until I did a speed test. Ran the RJ45 cable from the wall jack to the computer, ran the speed test and the whole computer locked up! Rebooted and again the same thing. Whats interesting is that I can play Doom all day long on the comcast connection but when i hoop up the fiber, no joy. I've got the latest bios and have reinstalled the drivers. I wouldn't think I need to purchase an external network card for the 1GB fiber speeds would I? Thoughts? Tks much

System // Windows 10 Pro x64