In the future please watch the unrelated linking...posts that include advertising have a way of disappearing.
In regards to your question:
"Does anybody know why I had to disable my firewall in order to install my new AT&T wireless gateway?"
We would need more information about your setup, including the OS(es), if this was a hardware or software firewall, which one, etc.
Help, my PC with Windows 10 won't shut down properly
Since upgrading to Windows 10 my computer won't shut down properly. I use the menu button shutdown and the screen goes blank, but the system does not fully shut down. The only way to get it to shut down is to hold the physical power button down till it shuts down. Any suggestions?