Asked this same question three years ago and no progress since then? Is there anything the new Spectrum doing for the IPv6 DNS servers? DNS queries are still done using IPv4.
All of their modern equipment works, the only thing is their DNS servers 1&2 are blocking IPv6. All you do is change the DNS settings in your router to googles, I think it's 8888 and 8866 but double check that.
Your "from work" post shows a modem with severe signal issues really bad correctables and needs to have the coaxial connections repaired. That maybe why it's having an IPv6 issue.
Nothing in either posts hint as to why IPv6 does or doesn't work.