Ok, I see the problem. Your router needs an external DNS server for it's internet setup.
You need to set DHCP to give your pihole server as the DNS to the computers INSIDE your network. It's impossible for your router to use your LAN DNS server on the WAN port.
I've never heard of spectrum doing this. I think it's an issue with your router. The steps you mentioned sound right, but I'm not seeing what you're seeing. I usually try to look at the advanced mode, which might have more info.
You could contact Netgear tech support, or consult their manual. Have you made sure you're on the latest firmware?
Jellyseer does just that. You browse popular media and click request and the torrent stuff is handled by the *arr's