OK, here's the scoop, from an AT&T lady in the Phillipines.
This ATT&T modem has a "dynamic" IP address.
The modem & what I call the router is all contained in the big box, which has the name AT&T U-verse printed on it.
She said that every time the modem re-boots, it's IP address will change.
Well, several people told us to unplug the big box, let it stay off for a few minutes, then plug it back in. So, we did that. That did not change the IP address.
It remained 107.126.64.82, which is the IP that is on the blacklist.
The lady told us to unplug the modem box, then also unplug the small box which is hooked to the antenna wire. She said they do not need to be unplugged for some long period of time. So, they were unplugged less than a minute. I had plenty of dumb questions for her, to occupy that time period.
TJ then plugged the small atenna box back in. The 2 lights on it came on. She then plugged the big box back in. I takes maybe around 3 minutes or so for all the lights on the big box to come back on. The green light labeled Wi-Fi blinks continually while the power stays on.
Once all the lights were back on, she told me to try to post on the site where I had been blocked, which I did. Was able to post just fine.
I thanked the lady & wished her a very nice day !
Since I was curious, I Googled something like "What is my IP address ?"
The 1st site I clicked on olny had the IPv6 IP. But, the next site also had the IPv4, which was now 107.126.68.25. So, only the last 3 numbers changed.
But, that IP address is NOT on a blacklist, at least not yet.
Anyhow, if this ever happens again, it won't be the big deal it was this time.
Many times, just a small amount of the correct info can be very helpful.