Internet Connectivity Problems

I'm told I must be a 'ONE OFF' as 2 levels of support have not been able to get me into an account so I can access the Spectrum streaming offers. They decided that my problem must be with my modem/router (AT&T). In spite of dealing with hundreds of websites over many years, Spectrum insists that my hookup is NOT LOCAL and directs me to do this at home (I'm sitting at my desktop at home during all of this effort). We (with support) get to the first screen, enter my email, generate a PSW - and get various errors preceded with 'Feature Not Available'. Examining the error codes all generate variations of "You must be at home to proceed". Not sure why Spectrum needs to know where I am but I definitely am sitting at home with the support person on the line. No matter how this sequence is approached, we always end up with the same result(s). I did contact AT&T and they did some diagnostics (even disabled the modem firewall for a test [didn't help]) and found nothing amiss about the modem. Today, I tried to 'sneak' in with a different ID but ended up the same. Personally, I feel this is an internal code problem within the Spectrum sign-in module (I have an extensive background in coding software) but cannot budge the web people to dive in and find it - their end position is that the problem is in my modem, despite Spectrum being the ONLY website I have visited that fails to work. I was wondering if anyone here has had a similar reception when trying to establish an account?